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A series of acylsulfenyl iodides (RCOSI) were synthesized by the reactions of carbothioic acid group 11–16 element derivatives with iodine or N-iodosuccinimides in moderate to good yields.

A series of Group 2 metal bis(arenecarbochalcogenoato)(crown ether) complexes M(EE'CAr)2(L)(L')x (M = Mg, Ca, Sr, Ba; Ar = aryl; E = S, Se; E' = O, S; L = H2O or THF; L' = 15-crown-5, 18-crown-6) were synthesized and their structures were revealed by X-ray analyses. The two carbothioato ligands in Mg, Ca and Sr 15-crown-5 complexes are located on the same side of the crown ether plane, while those in Mg, Ca, Sr, and Ba 18-crown-6 compounds are on both sides of the 18-crown-6 plane (trans relative to the plane). For the Ca 15-crown-5 complex, both carbothioato ligands are connected to the central Ca ion through an oxygen atom in a monodentate manner, and the two hydrogen atoms of the coordinated water molecule are intramolecularly hydrogen-bonded with thiocarbonyl sulfur atoms. One of the two carbothioate groups in the Ca 18-crown-6 complex is connected in a bidentate manner to the central metal, while the other is connected in a monodentate manner through an oxygen atom. The two thiocarboxylato ligands in the Sr 15-crown-5 congener are connected in a bidentate fashion to the same side of the crown ether plane. The Ca and Sr compounds are the first examples of alkali earth metal carbochalcogenoate complexes in which carbochalcogenolato ligands are connected in a monodentate manner through an oxygen atom. Both chalcogenoato ligands in Ba(SOCC6H4Me-4)2(18-crown-6) and Sr(SeOCC6H4Me-4)2(18-crown-6) are coordinated in a bidentate manner to the central metal ion.

The first ferrocenecarboselenoic acid was synthesized and characterized. The existence of tautomeric equilibrium between the selenol (FcCOSeH) and selenoxo forms (FcCSeOH) in polar solvents was proven by 1H-, 13C- and 77Se-NMR spectra. The selenoxo form exists predominantly in a polar solvent at low temperature below –70 °C. Treatment of this acid with lithium, sodium, and potassium hydrides and with rubidium and cesium fluorides gave the corresponding alkali metal ferrocenecarboselenoates in quantitative yields. Treatment with 4-methylphenyl isocyanate at room temperature led to ferrocenoyl 4-methylphenylcarbamoyl selenide FcCOSeC(O)NHC6H4Me-4 in high yield. A similar reaction with phenyl isothiocyanate formed a mixture of FcCOSeC(S)NHPh and FcCOSeC(SH)=NPh in moderate to good yield. The carboselenoic acid readily reacted with piperidine to give piperidinium ferrocenecarboselenoate in good yield. Air oxidation of this selenoic acid afforded diferrocenoyl selenide as a major product along with diferrocenoyl diselenide. The structures of the selenide (FcCO)2Se and diselenide (FcCOSe)2 were examined by single-crystal X-ray analysis.

Lithium, sodium, and potassium ferrocenecarboselenoates were synthesized in good yields by the reaction of ferrocenoyl chloride with the corresponding metal selenides. In air, the saltsquickly oxidized to give diferrocenoyl diselenide. The salts readily reacted with alkyl and organo-germanium, -tin and -lead halides to give the corresponding Se-alkyl and Se-organo Group-14 element ferrocenecarboselenoates [(FcCOSe)xMPh4–x (M = Ge, Sn, Pb; x = 1–3) in moderate to good yields. In contrast, the reaction of the sodium and potassium salts with trimethylsilyl chloride led to O-trimethylsilyl ferrocenecarboselenoate FcCSeOSiMe3. Treatment of the O-silyl ester with RbF and CsF led to rubidium and cesium ferrocenecarboselenoates, respectively, in good yields. The structures of FcCOSetBu, (FcCOSe)2SnPh2, and FcCOSePbPh3 were revealed by X-ray molecular structure analysis.

Compound (2-MeOC6H4CS)2S (1) showed an unusual saddle structure in which the –C(=S)–S–C(=S)– moiety is planar and two benzene rings lie a face-to-face and the distances (3.07 A) between the central sulfur atom and two 2-methoxy oxygen atoms are within the sum of van der Waals radii of the both atoms. However, the results of MO calculation at the B3LYP/6-311+G(2d, p) level showed no orbital interaction between both atoms. From the results of the calculations at the MP2 level, it was deduced that the crystal packing effect is important for such densely packed crystal, due to its less effective volume. On the other hand, the para-methoxy derivative (4-MeOC6H4CS)2S (2) in which the two methoxy oxygen atoms are not able to contact with the central sulfur atom shows an L-shaped structure in which the –C(=S)–S–C(=S)– moiety is not planar. The –C(=O)–S–C(=S)– moiety in compound (2-MeOC6H4CO)(2-MeOC6H4CS)S (3b) shows an L-shaped structure, though the two methoxy oxygen atoms are in intramolecular contact with the central sulfur atom. The deep blue to green colors of compounds 1 and 2 and the deep violet color of compound 3b are due to transitions of the lone-pair electrons in the HOMO (ψ87) of the thiocarbonyl sulfur atom to the LUMO (ψ89)and of those in the HOMO (ψ83) of the thiocarbonyl sulfur atom to the LUMO (ψ85), respectively.

The deprotonation of α-monosubstituted selenoamides with LDA followed by allylation gives γ,δ-unsaturated selenoamides in good to high yields. In the initial step, allylation may take place at the selenium atom of lithium eneselenolates to form allylic vinyl selenides, which then undergo seleno-Claisen rearrangement. As allylic bromides, γ,γ-disubstituted compounds such as geranyl and neryl bromides could also be used to give products that incorporated tertiary-quaternary stereogenicity with high efficiency.

A series of Te-1-acylmethyl carbotelluroates was prepared in good isolated yields from the reaction of potassium carbotelluroates with α-haloketones in acetonitrile. Thermolysis of the telluroesters afforded vinyl esters in 20−50% yields, while treatment of the carbotellurorates with potassium t-butanolate led to 1,3-diketones in 30−75% yields with the liberation of black tellurium. The reaction of potassium carbotelluroates with α-haloaceto oximes gave O-acyl oximes in 50−70% yields via Te-1-iminomethylcarbotelluroates.

The purpose of this study was to investigate the possibility of aromatic beta-selenolactams being used in agricultural chemicals. A series of beta-selenolactams with aromatic substituents at the 1-, 2- and 3-positions were synthesized and their bioactivities were evaluated. Acarianicidal and insecticidal activity against common destructive insects, antibacterial activity against seven common plant pathogens, and plant growth activity of typical food crops were investigated. We found that introduction of 4-chloro and 4-methyl groups on 2- or 3-phenyl groups of the beta-selenolactam ring brought about acarianicidal activity against adults and eggs of Plutella xylostella. However, except for moderate to weak effect on fatality of Culex pipiens molestus Forskal, insecticidal activity against two other kinds of insects, antibacterial activity against plant pathogens, and activity on plant growth regulation were not detected among the beta-selenolactam derivatives.

Sodium and potassium carbamotelluroates [M(R2NCOTe), M = Na, K, Rb, Cs] were synthesized in moderate to good yields by reacting carbamoyl chloride with the corresponding alkali metal tellurides. The salts readily reacted with trimethylsilyl chloride to form O-trimethylsilyl carbamotelluroate (R2NCTeOSiMe3), which further reacted with RbF and CsF to lead to the corresponding heavy alkali metal carbamotelluroates. These salts reacted with alkyl iodide and carbamoyl chlorides to give the corresponding Te-alkyl carbamotelluroates and dicarbamoyl tellurides in moderate yields.

This paper describes the synthesis and some reactions of potassium, rubidium, cesium and trimethylsilyl carbamoselenothioates. The potassium salts were synthesized in 70–80 % yields by reacting the corresponding thiocarbamoyl chlorides with potassium selenide in acetonitrile. Furthermore, the rubidium and cesium salts were obtained in good yields by treating the trimethylsilyl esters with the corresponding metal fluorides. The crystal structure of acetonitrile-solvated potassium N,N-dimethylcarbamoselenothioate consisted of dimeric units, featuring μ-carbamoselenothioate anions associated with potassium cations that are located on the upper and lower sides of a plane involving two opposing carbamoselenothioate groups. These heavier alkali metal salts readily reacted with alkyl halides to give both S- and Se-alkyl esters. The reaction of the potassium salts with trimethylsilyl chlorides forms S- and Se-trimethylsilyl carbamoselenothioates which are in equilibrium. The reaction of the salts and silyl esters with organo Group-14 and -15 elements halides gave exclusively the corresponding Se-substituted products in good yields.

A series of O-triorganosilyl carbamoselenoates were isolated in good yields from the reaction of sodium or potassium carbamoselenoates with triorganosilyl chlorides. The O-silyl carbamoselenoates readily reacted with RbF and CsF and with organo-germanium, -tin, and -lead halides and gave the corresponding heavy alkali metal and Se-substituted Group 14 organometal and carbamoselenoates in moderate to good yields.

A series of [(thioacyl)thio]- and (acylseleno)antimony and [(thioacyl)thio]- and (acylseleno)bismuth, i.e., (RCSS)xMR and (RCOSe)xMR (M = Sb, Bi, R1 = aryl, x = 1–3), were synthesized in moderate to good yields by treating piperidinium or sodium carbodithioates and -selenoates with antimony and bismuth halides. Crystal structures of (4-MeC6H4CSS)2Sb(4-MeC6H4) (9b′), (4-MeOC6H4COSe)2Sb(4-MeC6H4) (12c′), (4-MeOC6H4COS)2Bi(4-MeC6H4) (15c′), and (4-MeOC6H4CSS)2BiPh (18c) along with (4-MeC6H4COS)2SbPh (6b) and (4-MeC6H4COS)3Sb (7b) were determined (Figs. 1 and 2). These compounds have a distorted square pyramidal structure, where the aryl or carbothioato (= acylthio) ligand at the central Sb- or Bi-atom is perpendicular to the plane that includes the two carbodithioato (= (thioacyl)thio), carboselenato (= acylseleno), or carbothioato ligand and exist as an enantiomorph pair. Despite the large atomic radii, the CS ⋅⋅⋅ Sb distances in (RCSS)2MR1 (M = As, Sb, Bi; R1 = aryl) and the CO ⋅⋅⋅ Sb distances in (RCOS)xMR (M = As, Sb, Bi; x = 2, 3) are comparable to or shorter than those of the corresponding arsenic derivatives (Tables 2 and 3). A molecular-orbital calculation performed on the model compounds (MeC(E)E1)3−xMMex (M = As, Sb, Bi; E = O, S; E1 = S, Se; x = 1, 2) at the RHF/LANL2DZ level supported this shortening of CE ⋅⋅⋅ Sb distances (Table 4). Natural-bond-orbital (NBO) analyses of the model compounds also revealed that two types of orbital interactions nS σ and nS σ play a role in the (thioacyl)thio derivatives (MeCSS)3−xMMex (x = 1, 2) (Table 5). In the acylthio-MeCOSMMe2 (M = As, Sb, Bi), nO σ contributes predominantly to the orbital interactions, but in MeCOSeSbMe2, none of nO σ and nO σ contributes to the orbital interactions. The nS σ and nS σ orbital interactions in the (thioacyl)thio derivatives are greater than those of nO σ and nO σ in the acylthio and acylseleno derivatives (MeCOE)3−xMMex (E = S, Se; M = As, Sb, Bi; x = 1, 2). ▪The reactions of RCOSeSbPh2 (R = 4-MeC6H4) with piperidine led to the formation of piperidinium diphenylselenoxoantimonate(1−) (= piperidinium diphenylstibinoselenoite) (H2NC5H10)+Ph2SbSe−, along with the corresponding N-acylpiperidine (Table 6). Similar reactions of the bis-derivatives (RCOSe)2SbR1 (R, R1 = 4-MeC6H4) with piperidine gave the novel di(piperidinium) phenyldiselenoxoantimonate(2−) (= di(piperidinium) phenylstibonodiselenoite), [(H2NC5H10)+]2(PhSbSe2)2−, in which the negative charges are delocalized on the SbSe2 moiety (Table 6). Treatment of RCOSeSbR (R, R1 = 4-MeC6H4) with N-halosuccinimides indicated the formation of Se-(halocyclohexyl) arenecarboselenoates (Table 8). Pyrolysis of bis(acylseleno)arylbismuth at 150° gave Se-aryl carboselenoates in moderate to good yields (Table 9).

Ammonium eneselenolate 2 derived from selenothioic acid S-ester 1 was reacted with electron-deficient alkenes 4 and alkynes 9. Ammonium eneselenolate 2 underwent Michael addition with 4 to give two types of Michael adducts, 5 and 6. Products 6 incorporated two molecules of 4. In contrast, the reaction of 2 with 9 took place at the selenium atom to give γ-oxo divinyl selenides 10 with high Z-stereoselectivity. During the further elaboration of the reactivity of the products derived from 2 and carbonyl compounds, unexpected reaction was found in the addition of vinylmagnesium bromide to Se-vinyl ester 3. The spectroscopic data supported the formation of the enol form 12 of β-oxo selenothioic acid S-ester 13. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:187–192, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20003

Thioamide dianions were generated by the highly efficient reaction of N-benzyl thioamides with 2 equiv of BuLi. Alkylation, allylation, and silylation took place selectively at the carbon atom adjacent to the nitrogen atom of the thioamide dianions. Oxiranes and an aldehyde were also used as electrophiles in the reaction of thioamide dianions to form N-thioacyl 1,3- or 1,2-amino alcohols. The insertion reaction of elemental sulfur to a thioamide dianion and subsequent ethylation afforded a N-thioacyl hemithioaminal. NMR studies on the thioamide mono- and dianions derived from N-benzyl 2-methoxythiobenzamide showed a linear relationship between the chemical shifts of all carbon atoms of thioamide mono- and dianions. The results also suggested that the negative charge at the benzylic carbon atom of the dianion is not fully delocalized. The charge distribution patterns of the dianion are consistent with those of pi polarization.

The Peterson olefination of aromatic aldehydes with an alpha-silyl selenoacetamide proceeded smoothly with high stereoselectivity to give E-alpha,beta-unsaturated selenoamides in good to high yields. The reaction with aldehydes bearing alkenyl and dienyl groups gave the corresponding selenoamides bearing dienyl and trienyl groups, but the stability of the products depended on the substituents on the aromatic ring. X-ray molecular analysis disclosed that the alpha,beta,gamma,delta-unsaturated selenoamides had a nearly planar structure. In the (77)Se NMR spectra, signals were observed in the region greater than 130 ppm depending on the substituents on the aromatic ring, whereas the (1)J coupling constant between the carbon atom and the selenium atom was almost independent of the substituents. A linear relationship was observed between the chemical shifts in the (77)Se NMR spectra and Hammet sigma parameters, and this correlation was retained even when one or two alkenyl groups were introduced to alpha,beta-unsaturated selenoamides, although it became less sensitive.

The reaction of lithium eneselenolates generated from selenoamides with a variety of ketones proceeded smoothly at −78°C to give the corresponding β,β-disubstituted β-hydroxy selenoamides in moderate to good yields. The reaction showed high diastereoselectivity. The products obtained were converted to the corresponding amides by reacting them with cyclohexene oxide.

Group 14 element derivatives of carbotelluroates, RCOTeMPh 3 (M = Ge, Sn, Pb), were synthesized as stable compounds by reacting sodium carbotelluroates with Ph 3 MCl and were characterized by IR and 1 3 C and 1 2 5 Te NMR spectra. Their molecular structures were revealed by X-ray molecular analysis. The C=O...Sn distance in RCOTeSnPh 3 was found to be shorter than the C=O...Ge distance in RCOTeGePh 3 , despite the fact that the atomic radius of Sn is larger than that of Ge. A similar shortening of the nonbonding distance was observed for the corresponding selenium derivatives. Molecular orbital calculations of model compounds, i.e., CH 3 COEM(CH 3 ) 3 (E = Se, Te; M = Ge, Sn, Pb), at the B3LYP/LANL2DZ+p level also supported this shortening of the C=O...Sn distance. NBO (natural bond orbital) analyses of the model compounds showed that two types of orbital interactions, n O →σ * M E and n O →σ * M C (E = S, Se, Te; M = Ge, Sn, Pb), are important in these carbochalcogenoates. Furthermore, the former interaction has a greater role in the case of carbothioates, whereas the latter is dominant in carbotelluroates.

Ammonium eneselenolates were generated with high efficiency by reacting selenothioic acid S-esters with a THF solution of TBAF. The methylation of ammonium eneselenolates gave ketene selenothioacetals as stereoisomeric mixtures. The ratio of the two stereoisomers depended on the duration of the reaction before the addition of MeI. Ammonium eneselenolates were characterized by examining their (1)H, (13)C, and (77)Se NMR spectra, which indicated that ammonium eneselenolates were present almost exclusively as Z-isomers. These results suggested that ammonium eneselenolates are kinetically generated as stereoisomeric mixtures, and isomerization of E-isomers to Z-isomers then takes place to result in the exclusive formation of Z-isomers. During the methylation of Z-isomers of ammonium eneselenolates, the isomerization of Z-isomers to E-isomers occurs to give stereoisomeric mixtures of ketene selenothioacetals. NMR spectra of ammonium eneselenolates implied that the electrons at the selenium atom are somewhat delocalized to the carbon-carbon double bond and the carbon-selenium bond shows partial double-bond character.

Aldol-type condensation reactions of α-monosubstituted selenoamides with a variety of aldehydes are examined to furnish β-hydroxy selenoamides in good to high yields. The use of selenoamides derived from dibenzylamine exhibits high stereoselectivity. As for the reaction with aliphatic aldehydes selenoamides show better yields and selectivity compared with ordinary amides. Conversion of the resulting β-hydroxy selenoamides to 1,3-amino alcohols is also described.

The efficient generation and alkylation of ammonium ene selenolates have been described. The synthesis of ketene seleno thioacetals having a variety of functional groups was attained. The stereoselectivity of the generation of ammonium eneselenolates was compared between selenoic acid O-esters and selenothioic acid S-esters.

The reaction of lithium eneselenolates and dieneselenolates derived form selenoamides with a variety of carbonyl compounds has been described. In the reaction with α,β-unsaturated esters and ketones Michael addition reaction took place very rapidly, whereas the reaction with α,β-unsaturated aldehydes gave selectively 1,2-adducts. As for the reaction of lithium dieneselenolates ally1 group and aldehydes were selectively introduced to the position α to the selenocarbonyl group.

Selenocarboxylic acids [RC(=O)SeH] were found to readily react with aryl, acyl, and arenesulfonyl isocyanates to give the corresponding acyl carbamoyl selenides 3 [RC(=O)SeC(=O)NHR′, R′ = aryl, C6H5CO, and 4-MeC6H4SO2] in good yields. Their tautomers [RC(=O)SeC(=NR′)OH] were also detected by 1H, 13C, and 77Se NMR spectroscopies. The structure of 3 [R = 2,6-(MeO)2C6H3, R′ = 4-MeC6H4] was characterized by X-ray crystallography, which showed that this molecule is stabilized by an intramolecular hydrogen bond between the carbonyl oxygen and the NH hydrogen to form a planar six-membered ring and by nonbonded interaction of the ortho methoxy oxygen with the carbonyl oxygen or the selenium atoms. 4-Methoxybenzoyl and 4-methoxythiobenzoyl N-(4-methylphenyl)carbamoyl sulfides (4 and 5) were shown by X-ray crystallography to similarly have a planar intramolecular six-membered ring formed by a hydrogen bond between the carbonyl oxygen or thiocarbonyl sulfur and NH hydrogen atoms. The tautomers [RC(=E)SC(=NR′)OH; E = O or S] of 4 and 5 also were detected spectroscopically. The reactions of 3h (R = 4-MeOC6H4, R′ = Ph) with sodium methoxide and p-toluidine gave sodium selenocarboxylate and the corresponding amides and urea as main products, respectively. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:250–258, 2001

A series of thioacylsulfanylarsines ((RCS2)AsPh2, (RCS2)2AsPh, (RCS2)3As) were synthesized by treating piperidinium dithiocarboxylates with Ph2AsCl, PhAsCl2 or AsCl3, respectively and characterized. Their molecular structures were determined by X-ray crystallography and compared with those of the corresponding acylsulfanyl derivatives ((RCOS)AsPh2, (RCOS)2AsPh, (RCOS)3As). They exist as monomers, and the environment around the arsenic atoms is distorted tetrahedral with one lone pair at the apex. The structure of the mono(dithiocarboxylate) is different from that of the corresponding thiocarboxylic acid derivative, while the bis and tris derivatives showed similar structure to the corresponding thiocarboxylic acid derivatives ((RCOS)2AsPh, (RCOS)3As), respectively. The new compounds showed intramolecular interactions between the thiocarbonyl sulfur and the central arsenic atom. NBO (Natural Bond Orbital) analyses performed on the model compounds (CH3CS2)As(CH3)2 and (CH3CS12)(CH3CS22)AsCH3 at the RHF/LANL2DZ level of theory showed the presence of interactions between the non-bonding orbitals on the thiocarbonyl sulfur (nS) and the σ*MS orbitals together with that between the nS and the σ*MC orbitals for the former compound; for the latter the presence of both orbital interactions between nS and σ*MS1 and between ns and σ*MS2 are present. The reaction of the mono(dithiocarboxylate) derivative (R = 4-CH3C6H4) with piperidine in ethanol gave piperidinium diphenyldithioarsinate along with the corresponding N-thioacyl- or N-acyl-piperidine. A similar reaction of the bis(dithiocarboxylate) derivative (R = 4-CH3C6H4) gave the novel di(piperidinium) phenyltrithioarsonate in which two anion charges are delocalized on the AsS3 moiety and a cyclic phenylarsine sulfide tetramer (PhAsS)4. The diphenyldithioarsinate and phenyltrithioarsonate salts exist as a dimer and a polymer, respectively, in which 12-membered rings are formed by intermolecular N–H ⋯ S hydrogen bonds.

A series of RCSSGePh3, (RCSS)2GePh2, (RCSS)3SnPh, and (RCSS)2PbPh2 were synthesized, and the structures of some p-tolyl derivatives [RCSSMPh3 (R=4-CH3C6H4, M=Ge: 1d, Sn: 3d, Pb: 6d) and (4-CH3C6H4CSS)2SnPh2 (4d)] and a o-tolyl derivative [(2-CH3C6H4CSS)3SnPh: (5c)] were analyzed by X-ray. The results indicate intramolecular non-bonded interactions between the thiocarbonyl sulfur and the central Group 14 element metals. The mono dithiocarboxylates (1d, 3d, and 6d) exhibit a distorted tetrahedral structure around the central Group 14 elements. Diphenyltin bis(dithiocarboxylate) (4d) is shown to take a distorted octahedron or skewed trapezoidal bipyramid, where the two dithiocarboxylate groups are bound to the Sn atom as an anisobidentate ligand, and the tin tris(dithiocarboxylate) (5c) exhibits a seven-coordinated pentagonal bipyramid. The distance between the thiocarbonyl sulfur and the Sn atom in 4-CH3C6H4CSSMPh3 (M=Ge, Sn, Pb) is shorter than those in the corresponding germanium and lead derivatives. Based on these distances, the affinity of Group 14 elements for sulfur atoms is deduced to decrease in the order Sn>Pb≥Ge>Si>C.

Stoichiometric reactions of alkali metal thio- and dithiocarboxylates with Ph2PCl, PhPCl2, and PBr3 gave the corresponding acylthio- and thioacylthiophosphines [(RCES)nPPh3-n, E = O, S; n = 1—3] 3—8 in moderate to good yields. The structures of (4-CH3C6H4COS)nPPh3-n (3d: n = 1, 4d: n = 2, 5d: n = 3) and (4-CH3C6H4CS2)2PPh (7b) were analyzed by X-rays. In the thiocarboxylate derivatives 3d, 4d, and 5d, the intramolecular interactions between the carbonyl oxygen and the central phosphorus atoms are weak and the thiocarboxylato ligands act as monodentates through the sulfur atoms. Similarly, in the dithiocarboxylate derivative 7b, the intramolecular interactions between the thiocarbonyl sulfur and the central phosphorus atoms are weak and the dithiocarboxylato ligands act as monodentates. The covalent phosphorus-sulfur and/or phosphorus-phenyl ipso-carbon bonds are nearly at right angles to one another, forming a distorted tetrahedron with the unshared electron pair orbital at the apex. The 31P NMR spectra o...

The reaction of selenothioic acid S-esters 1 with trialkyl phosphites proceeds smoothly with the extrusion of selenium atoms to afford α-phosphoryl sulfides 2 in good to high yields. A similar reaction takes place more easily with dimethyl phenylphosphonite and methyl diphenylphosphinite, although the ketene selenothioacetals 3 are also formed as by-products in increased yields. The use of diselenoic acid esters 1f and 1g gives α-phosphoryl selenides 2m and 2n. The products exhibit characteristic chemical shifts and coupling constants in their 31P NMR spectra. The structure of α-phosphoryl selenide 2n is confirmed by X-ray molecular structure analysis. The reaction with triphenylphosphine leads to oxidative dimerization of ester 1d to give divinyl diselenide 4 in good yield. A catalytic amount of triphenylphosphine is also effective to form divinyl diselenide 4. The reaction may begin with the nucleophilic attack of triphenylphosphine on the carbon atom of the selenocarbonyl group of ester 1d. Details of the reaction pathway leading to α-phosphoryl sulfides 2 are also discussed. The reaction with menthyl diphenylphosphinite 12 has suggested that the reaction may proceed via initial nucleophilic attack of trivalent phosphorus compounds bearing alkoxy groups on the selenium atom of esters 1. The intermediacy of phosphonium ylide 14 has also been supported by the reaction of the ester 1h which gives 1,4-oxathiane 15.

Bis(phosphine)bis(tellurocarboxylato)-palladium(II) and -platinum(II), [M(RCOTe)2(PR′3)2] (M = Pd or Pt; R = But, Ph, 4-MeC6H4, etc.; R′ = Et or Ph), were synthesized in moderate to good yields by treating sodium tellurocarboxylates or O-trimethylsilyl telluroesters with [MCl2(PR′3)2]. The platinum complexes with 2-methoxybenzenecarbotelluroato ligands also were synthesized from [Pt(PR′3)4] with the corresponding diacyl ditelluride. The tellurocarboxylato complexes are yellow to orange or red crystals, and labile thermally and toward oxygen. The nickel analogues [Ni(RCOTe)2(PR′3)2] (R′ = Et or Ph) were obtained by similar fashion, but were too labile to isolate. X-Ray diffraction analysis of trans-[Pt(4-MeC6H4COTe)2(PEt3)2] was carried out, and compared with those of the corresponding thio- and seleno-carboxylato complexes. These complexes crystallized in the same space group (P21/c) and are isostructural having a square-planar co-ordination geometry with thio- or telluro-carboxylato ligands which are unidentate.

α, α-Disubstituted selenoamides were easily converted to unsymmetrical ketones in high yields by the reaction with alkyllithiums, whereas the reaction with alkynyllithium and methyl iodide gave α, β-unsaturated ketone and dialkynylamine.

The reaction of lithium alkyneselenolates generated from terminal acetylenes, butyllithium, and selenium with amines and allylic bromides proceeded smoothly in THF at 67 °C to give 4-penteneselenoamides in moderate to high yields. The reaction may proceed via selenoketene intermediates bearing an allylic group, followed by the attack of amines to give the products. Aliphatic and aromatic acetylenes, silylacetylene, and enynes were employed as terminal acetylenes. One molar amount of secondary amines was effective, whereas an excess of primary amines was necessary. The reactions with 2-butenyl bromide exhibited high regioselectivity, although they gave the stereoisomeric mixtures. The reactions of silyl ethers of propargylic alcohols gave α,β-unsaturated selenoamides as a product.

This review covers synthetic methods of three types of selenium counterparts of dithioic acid esters, e.g. selenothioic acid Se-esters, selenothioic acid S-esters, and diselenoic acid esters. These generally utilize a combination of electrophilic thio- or seleno-acylating agents and nucleophilic organoselenium or -sulfur compounds. Observed trends in the stability of the esters are also discussed.

Rh(II) acetate effectively catalyzed the hydrosilylation of enamides, N-vinylurea, and imides to give N-(silylalkyl)amide derivatives in moderate to high yields. The silyl group was selectively introduced to the carbon atom adjacent to the nitrogen atom, whereas the efficiency and regioselectivity of the Rh-catalyzed hydrosilylation of vinyl carboxylates, thiocarboxylates, ethers, and thioethers were highly affected by the substitution patterns of the substrates and reaction conditions. The reaction of N-vinylphthalimide (1f) with deuteriosilane suggests that the catalytic process involving the oxidative addition of hydrosilane and migratory insertion of the alkenyl group of 1f is reversible. The molecular structures of the N-(1-silylethyl)phthalimide 2f and N-(1-silylethyl)acetamide 2k species have been determined by X-ray analyses. The results show that there is no intramolecular interaction between the silicon atom and the oxygen atom of the carbonyl groups of 2f and 2k.

A series of selenocarboxylic acids and their alkali metal salts were prepared. The potassium, rubidium and cesium salts are foundamentaly dimeric structure. Selenocarboxylic acids exist predominantly in selenon acid (selon acid) at low temperature in polar solvent. Selenocarboxylic acids readily react with aryl isocyanates to acyl carbamoyl selenides in good yields.

The reaction of selenoic acid O-methyl esters with aluminum thiolates and selenolates proceeded smoothly to give a variety of selenothioic acid S-esters and diselenoic acid esters in moderate to good yields. The stability of the esters obtained were compared.

Selenothioic acid S-alkyl esters were synthesized from the reaction of terminal acetylenes with n-butyllithium, selenium, and alkanethiols in moderate to high yields. The use of substituted benzene...

Selenothioic acid S -alkyl esters were reacted with allylic bromides in the presence of Et 3 N. Mono-, di- or tri-allylatd products were selectively formed by changing reaction temperatures, times and allylic bromides used. The reaction proceeded with high regio- and stereoselectivity via the seleno-Claisen rearrangement. The selective synthesis of monoallylated esters was also attained by the reaction of in-situ generated lithium eneselenolates with allylic bromides.

The report covers the synthesis, spectra, structures and reactions of diacyl mono- and diselenides and tellurides, acyl thioacyl mono- and disulfides, and (dithioacyl) mono-, di-, tri- and tetrasulfides.

Initial alkylation may take place at the selenium atom to give allylic vinyl selenide followed by a seleno Claisen rearrangement.

The reaction of lithium alkyneselenolates generated from terminal acetylenes with thiols gave rise to lithium eneselenolates with high stereoselectivity. The trapping with alkyl halides afforded ketene selenothioacetals, whereas the trapping with allylic bromides yielded γ,δ-unsaturated selenothioesters via seleno-Claisen rearrangement.

Thiocarboxylic acids, such as selenocarboxylic acids, exist predominantly in the thioxo form (RCSOH, thion acid) in polar solvents such as tetrahydrofuran (THF) at temperatures below −50 °C. Tellurocarboxylic acids (5) were observed for the first time by acidolysis of the corresponding cesium tellurocarboxylates with hydrogen chloride. The telluroic acids (6) exist predominantly in the telluroxo form (RCTeOH, telluron acid) in THF at temperatures below −70 °C. Telluron acids were reddish to blue violet for the aliphatics (R = alkyl) and dark green for the aromatics (R = aryl) and reacted with aryl isocyanates at −70 °C to give crystalline acyl carbamoyl tellurides in good yields.

A series of rubidium and cesium tellurocarboxylates (2 and 3) were synthesized from the reaction of O-trimethylsilyl tellurocarboxylates (1) with rubidium and cesium fluorides in moderate isolated yields and characterized by 1H, 13C, and 125Te NMR spectroscopy and X-ray diffraction. The carbon–oxygen distance [1.235(6) A] of the tellurocarboxyl group of crystalline cesium 2-methoxybenzenecarbotelluroate (3f) showed a typical value of the carbon–oxygen double bond. The crystal packing of 3f shows the possibility of an interaction between the cesium cation and the aromatic ring carbon. The thio- and selenocarboxyl groups of the corresponding sulfur and selenium isologues (4 and 5) also indicate a double bond [1.231(4) and 1.226(5) A] between the carbon and oxygen, respectively. The salts (2 and 3) readily react with iodomethane to afford the corresponding Te-methyl tellurocarboxylates in good yields. The reaction between 3 and tetramethylammonium chloride was found to give a novel quaternary ammonium salt (...

Aromatic diselenoic acid Se-methyl esters 1 react with amines at 0°C in tetrahydrofuran (THF) to yield selenoamides in moderate to good yields. The reaction course is highly dependent on the steric requirements of both starting materials. In the reactions of the ester 1a with 2-methylpiperidine and of the ester 1b with piperidine, the starting materials disappear within 1 hour with the liberation of black selenium, but the corresponding selenoamides are not produced. These results may be ascribed to the steric congestion caused by the formation of the selenoamide group from the tetrahedral intermediate 15. X-ray crystal structure analyses of the selenoamides 3 and 9 have been performed. The bond length of C(Se)N is shorter than a carbon nitrogen single bond. On the other hand, the CSe bond is longer than that of the ordinary carbon-selenium double bond. These results are indicative of the efficient delocalization of the electrons of nitrogen to the carbon–selenium double bond. The double bond character between the carbon attached to selenium and the nitrogen is also supported by the nitrogen atom showing sp2 character. When a methyl group is introduced at the meta position of the aromatic ring, the deviation of the aromatic ring from the plane involving the carbon–selenium double bond and nitrogen atom becomes substantially large, perhaps due to the steric bulkiness of the selenium atom.

Sodium 2 and potassium selenocarbamates 3 were found to be synthesized in moderate to good yields by the reaction of carbamoyl chlorides with sodium and potassium selenides. The salts 2 and 3 reacted with alkyl halides and organo-germanium, -tin, and -lead chlorides to give the corresponding esters 7–9 in good yields.

Lithium 1-alkoxyeneselenolates 2 in tetrahydrofuran were characterized by 1 H NMR for the first time. Their reaction with propargyl bromide was found to proceed through a propargylic rearrangement to generate allenic selenoic acid O -esters 3 , which led to poly-substituted selenophenes in moderate yields under reflux.