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A novel multicomponent reaction of arynes, [beta]-keto sulfones and Michael-type acceptors has provided an efficient method for the synthesis of polysubstituted naphthols and polysubstituted naphthalenes. It is shown that the tandem reaction might proceed via a sequential nucleophilic attack to arynes, intramolecular nucleophilic substitution followed by a Michael addition and a ring closure-elimination process.

(1E,2E)-3-Bromo-4-oxo-N'-tosyl-2-alkenoxylimidic acid ethyl esters are prepared via a novel reaction pathway of 2,3-allenoates with an electrophile (TsN[Br.sub.2]) in the presence of [K.sub.2]C[O.sub.3]. The reaction has proceeded in a highly stereoselective way and a plausible mechanism is proposed for rationalizing this reaction.

The nucleophilic addition of sodium azide to 1,2-allenyl esters has produced vinyl azides with very good regio- and stereoselectivities. A new method is developed for the synthesis of pyrroles from 1-allylic allenyl esters through a series of consecutive transformations.

Conformationally constrained chiral PNA analogues are designed on the basis of stereospecific imposition of a 1,2-cis-cyclopentyl moiety on an aminoethyl segment of aegPNA. Hybridization studies with complementary DNA and RNA sequences using UV-T(sub m) measurements indicate that aeg-cpPNA chimera form thermally more stable complexes than aegPNA with stereochemistry-dependent selective binding of cDNA/RNA.

The halohydroxylation of 1,2-allenyl sulfides or selenides with Br(sub 2) (CuBr(sub 2) or NBS) or I(sub 2) and water demonstrate a fair good regioselectivity leading to the synthesis of synthetically important 3-organosulfur or seleno-2-haloallylic alcohols. The conclusion states that the stereoselectivity depends on the nature of X(super +) and S or Se, showing a Z-selectivity with the matched Lewis acid-base pair.

Research has been conducted on beta-phenylseleno-alpha-tolylsulfonyl-substituted alkenes. The synthesis of these compounds carried out via the three-component conjugated-nucleophilic addition of acetylenic sulfones, phenylselenomagnesium bromide and carbonyl compounds is described.

Research has been conducted on alpha-hypervalent iodine functionalized phosphonium and arsonium ylides. The use of these compounds as umpolung ylides in the reactions with nucleophiles carried our to allow alpha-heteroatom substituted ylides is described.

Research has been conducted on the polymer-bound cyclic malonic acid ester. The preparation of this ester developed via the use of Merrifield resin and the solid-phase reaction of the ester with binucleophiles are described.

Research on bifunctionalized vinyl tellurides paves the way for the stereo- and regioselective synthesis of vinyltellurides containing sulfonyl, phosphonyl, and iodo groups from stereo- and regiodefined addition of tellurides with alkynes. Data show that arylsulfinate serves as a sulfonyl radical precursor, while diaryl ditellurides as radical acceptors.

Research describes a unique regio- and stereoselective carbonylation reaction of acetylene selenides catalyzed by palladium(II). Data show that the synthetic approach employed results in high yield of 2-seleno-3-chloroacrylates under mild conditions.

The synthesis of highly substituted acryl imide derivatives by the three-component reaction of allenoates, isocyanides and carboxylic acids is described. The intramolecular cyclization reaction of allenoic acids with isocyanides is discussed.

An effective approach is described for the total synthesis of natural antibiotic pamamycin 621A, in which the stereogenic centers at the C-13 and C-15 are taken from a chiral building blocks derived from the D-glucolactone while all others are installed via chiral auxiliary-induced asymmetric Evans/Crimmins aldol reactions. The basic dimethylamino functionality at the C-15 is installed at the final stage of the whole synthesis, with those side reactions in the conversion of the azido group effectively circumvented by using a very mild yet largely forgotten tributyltin reduction protocol.

A simple synthesis of xanthenes and acridines based on a cascade nucleophilic addition-cyclic Michael addition process of arynes and phenols/anilines substituted with [alpha],[beta]-unsaturated groups at the ortho positions is described. The reaction could also be successfully adapted for the synthesis of 9-spiro-xanthene and acridine derivatives with potential biochemical interest.

A versatile and general one-pot synthesis of substituted isoindolinones from 2-furaldehydes, amines, 2-(phenylselanyl)acrylic acids, and isocyanides is described. The tandem process involved the Ugi four-component condensation, intramolecular Diels-Alder cycloaddition, and subsequent deselenization-aromatization promoted by B[F.sub.3]-O[Et.sub.2].

1-Naphthaldehydes and 3-oxabicyclo[3.1.0]hexan-2-ols is prepared by the intramolecular alkylation and cyclization of (E)-2-(arylmethylene)cyclopropylaldehyde mediated by different organo-selenium reagents. The properties of selenium reagents have played a major role in the reactions.

The selectivity of the halohydroxylation of 1-cyclopropylallenes reaction generated two multisubstituted C=C double bonds at the same time to yield 5-halo-hexa-3,5-dien-1-ols. The halohydroxylation of 1-cyclopropylallenes and alkynyl-substituted conjugated dienes could find application in organic synthesis.

A new method is described for the stereoselective synthesis of bifunctional methlylenecyclobutanes by using the Zn[Cl.sub.2]-mediated reactions of (E)-2-(arylmethylene)cyclopropylaldehyde with various acyl chlorides. The reaction could be applied to obtain 1,3-conjugated dienes through distal-bond cleavage.

CAN-mediated oxidative rearrangement of various vinyldenecyclopropanes has generated unsymmetrical divinyl ketone and functional enone derivatives in good yields with excellent regio- and stereoselectivities. The reaction mechanism is examined based on an oxygen-18 tracer experiment.

The simple iodohydroxylation reaction of alkylidenecyclopropanes (ACPs) with [I.sub.2] and [H.sub.2]O was used to prepare a variety of iodocyclopropylmethanol and 3-iodobut-3-en-1-ol derivatives. The products obtained bearing two functional groups -X and -OH could be converted to other interesting and useful structural units in organic synthesis.

A convenient and highly efficient method is presented for the synthesis of beta-organotellurobutenolides by the aryltellurenyl halides-induced electrophilic tellurolactonization of alpha-allenoic acids under mild conditions. The obtained tellurobutenolides are practical precursors for useful substituted butenolides.

The reaction of benzylidenecyclopropane with 2 equiv of Mn(OAc)(sub 3).2H(sub 2)O and 1 equiv of malonic acid diethyl esters in acetic acid, at 80 degrees Celsius, was examined. Results showed dihydronaphthalene derivatives in moderate yields.

The full details of the copper-mediated cyclization reaction of cyclopropylideneacetic acids (or esters) and cyclopropylideneacetonitriles are presented. The synthetic application of this reaction and the study of the reaction mechanism are discussed.

Research has been conducted on 1-alkenyl sulfoxides or sulfones. The hydrozirconation reaction of these compounds with Cp (sub)2 Zr(H)Cl in tetrahydrofuran at room temperature is described.

An interesting sequential three-component reaction provides a facile synthesis of selenium/sulfur-substituted 3-oxabicyclo[4.2.0]octa-1(8),5-diene and tetrahydro-1H-isochromene from lithium alkylselenolates or alkylthiolates, 1-alkynylphosphine oxides, and aldehydes. The sequential reaction proceeds via a conjugate addition/condensation/elimination process to form the allene intermediate, which subsequently underwent [2 + 2] or [4 + 2] cyclization reaction to afford bicyclic frameworks. [ABSTRACT FROM AUTHOR]

A facile synthesis of xanthenes and acridines based on a cascade nucleophilic addition-cyclic Michael addition process of arynes and phenols/anilines substituted with α,β-unsaturated groups at the ortho positions is described. The reaction has also been successfully extended to the synthesis of 9-spiro-xanthene and acridine derivatives with potential biochemical interest. [ABSTRACT FROM AUTHOR]

The cycloadditions of vinylidenecyclopropanes with aldehydes for the synthesis of tetrahydrofurans are detailed in this paper. The obtained polysubstituted tetrahydrofurans could serve as versatile intermediates to selectively produce furan, indene, and benzo[c]fluorene derivatives depending on the substituents at the tetrahydrofurans' rings arid the varied reaction conditions, which clearly exhibit insights into the synthetic applications of tetrahydrofurans. The scope, limitations, and mechanisms of these transformations have been discussed in detail. Attractively, these cycloadditions of vinylidenecydlopropanes with aldehydes and the further transformations of the cycloadducts provide an efficient protocol for the construction of various medium- and large-size ring-fused tetrahydrofuran, furan, and benzo[c]fluorene derivatives. [ABSTRACT FROM AUTHOR]

A novel multicomponent reaction of arynes, β-keto sulfones, and Michael-type acceptors is presented, providing an efficient method for the synthesis of polysubstituted naphthols and polysubstituted naphthalenes. Further investigation suggests that the tandem reaction may proceed via a sequential nucleophilic attack to arynes, intramolecular nucleophilic substitution followed by a Michael addition, and a ring closure-elimination process. [ABSTRACT FROM AUTHOR]

We report a convenient and highly efficient method for the synthesis β-organotellurobutenolides by the aryltellurenyl halides-induced electrophilic tellurolactonization of α-allenoic acids under mild conditions. The resulting β-organo-tellurobutenolides can be utilized as precursors for versatile butenolide derivatives through a substitution reaction with organocuprate reagent or Pd]Cu(I)-catalyzed cross-coupling with terminal alkyne. [ABSTRACT FROM AUTHOR]

β-Phenylseleno-α-tolylsulfonyl-substituted alkenes were synthesized via the three-component conjugate-nucleophilic addition of acetylenic sulfones, phenylselenomagnesium bromide, and carbonyl compounds, such as aldehydes, aliphatic ketones, or α,β-unsaturated enals or enones. The reaction is highly regio- and stereo-selective with moderate to good yields. Functionalized allylic alcohols were obtained in the case of aldehydes and aliphatic ketones. In the case of α,β-unsaturated enones, functionalized allylic alcohols or functionalized γ,δ-unsaturated ketones were obtained, depending on the structures of the ketones. [ABSTRACT FROM AUTHOR]