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Lewis-base coordinated iminoborane adducts, in contrast to their isoelectronic analogue imines, remain largely unexplored given the lack of efficient synthetic strategies for generating robust compounds. Herein, we report the preparation of a cyclic amino iminoborane carbene complex 2 obtained in quantitative yield by adding NHC to the 1,8-(trimethylsilyl)aminonaphthalene complex of boron 1 to induce the elimination of trimethylsilyl chloride (TMSCl). The iminoborane-NHC adduct 2 shows unprecedented thermal stability both in the solid and solution phases, due to the rigid, pre-established geometry of the 1,8-diaminonaphthalene scaffold. Theoretical calculations reveal an exceptionally strong iminoborane-NHC bond as a consequence of the enhanced boron-center acidity in combination with the lower steric and electronic shielding. We show that the chemical bond can be understood as donor-acceptor interaction, leading to a different kind of electronic situation of the B═N π-bond. The high conjugation between the pz-lone pair of the tricoordinated sp2 hybridized N atom and the B═N π-system results in a particularly long B═N double bond distance. Taking advantage of the pendant lone pair of the dicoordinated sp2 hybridized N atom, the iminoborane-NHC adduct gives access to NHC-stabilized borenium cation 3 through the reaction with trimethylsilyl triflate (Me3SiOTf) or to the gallium adduct 4 by reacting with GaCl3. Incorporating an iminoborane functional group into a π-conjugated system brings a new bonding situation for broadening the scope of BN-containing polyaromatic systems.

Background: Ketone is abundant in many natural products and in pharmaceuticals. It is believed to be one of the important functional groups in organic chemistry. Till date,several research approaches have been made to access ketone from a readily available starting materials. One such notable transformation consists of the conversion of carboxylic acid to the corresponding ketone in a one pot manner. Objective: We aimed to develop a simple one pot reaction for the conversion of carboxylic acid to ketone. This reaction could be useful to convert all types of carboxylic acid to ketone in a facile manner. Methods: In this procedure, a carboxylic acid has been converted to the corresponding trimethylsilyl ester using trimethylsilyl chloride in the presence of a base. A suitable organometallic reagent can interact with the ester formed at 20°C to produce the corresponding ketone. Results: Under the optimized reaction conditions, various aromatic, aliphatic and heteroaromatic carboxylic acids have been converted to the corresponding ketones using organolithium reagents, in a one pot manner. Moderate to good yields of the desired ketones were observed in most of the transformations. Conclusion: Conversion of carboxylic acid to ketone has been reported in a one pot fashion, where carboxylic acid has been transformed to its silyl ester. Organolithium reagents were used as nucleophile for our reaction purpose, whereas the organomagnesium reagents were not useful for this transformation. Aliphatic, aromatic and heteroaromatic carboxylic acids have been converted to the ketones following a simple process.

The reactivities of poly(alkoxycarbonylmethylene)s under basic conditions are described. The reactions of poly(ethoxycarbonylmethylene) (polyEDA′) and poly(benzyloxycarbonylmethylene) (polyBDA′) with a mixture of lithium diisopropylamide and trimethylsilyl chloride transformed a part of the repeating units (ca. 25 and 50 mol% for polyEDA′ and polyBDA′, respectively) into ketene silyl acetal frameworks. The ketene silyl acetal units were partially alkylated by the reaction with a mixture of tetrabutylammonium fluoride (TBAF) and an electrophile (methyl iodide and benzyl bromide), affording poly(substituted methylene)s with quaternary carbon atoms in the main chain, with the highest incorporation of 13 mol% being attained in the methylation of silylated polyBDA′. TBAF was found to effectively cleave carbon–carbon bonds in the main chain of polyEDA′ and polyBDA′ at room temperature for 1 h, yielding poly(alkoxycarbonylmethylene) oligomers with well-defined chain end structures with a much higher frequency of cleavage than that observed with their vinyl polymer counterparts, poly(alkyl acrylate)s.

A one-step synthesis of acyl phosphoramidates from a variety of functionalized acyl azides has been developed employing trimethylsilyl chloride as an activating agent in a modified Staudinger reaction. The methodology was further adapted to include the in situ generation of the acyl azides from a diverse selection of carboxylic acids and hydrazide starting synthons. The reaction scope was extended to include the synthesis of imidodiphosphates and the natural product Microcin C.

A new method for the synthesis of α-branched amines by reductive functionalization of tertiary carboxamides and lactams is described. The process relies on the efficient and controlled reduction of tertiary amides by a sodium hydride/sodium iodide composite, in situ treatment of the resulting anionic hemiaminal with trimethylsilyl chloride and subsequent coupling with nucleophilic reagents including Grignard reagents and tetrabutylammonium cyanide. The new method exhibits broad functional-group compatibility, operates under transition-metal-free reaction conditions, and is suitable for various synthetic applications on both sub-millimole and on multigram scales. Ministry of Education (MOE) Nanyang Technological University Accepted version This work was supported by funding from Nanyang Technological University (NTU) (for S.C.), the Singapore Ministry of Education (Academic Research Fund Tier 2: MOE2017-T2-1-064 for S.C.).

4-Chloroisocoumarins can be conveniently prepared from 2-alkynylaryloate esters via the activation of alkynes by electrophilic chlorine, generated in situ from N-chlorosuccinimide (NCS) in the presence of 10 mol % trimethylsilyl chloride (TMSCl), which leads to 6-endo-dig-selective chlorinative annulation to give the desired products in moderate to quantitative yields. The procedure employs readily available reagents and can be conveniently carried out on a wide scope of substrates under mild conditions (0 °C to rt). Furthermore, the reaction is scalable for gram-scale preparation of 4-chloroisocoumarins. Additionally, 4-bromo- and 4-iodoisocoumarins can be prepared in moderate to good yields by replacing NCS with N-bromosuccinimide (NBS) and N-iodosuccinimide (NIS), respectively.

The electroreductive coupling of 1-alkoxycarbonyl-4-quinolones with benzophenones in the presence of trimethylsilyl chloride gave adducts reacted at the 2-position of 4-quinolones as trimethylsilyl ethers. The adducts were transformed to 2-(diarylhydroxymethyl)-4-quinolones. The electroreduction of 1,3-diethoxycarbonyl-4-quinolones and polyhalogenated 3-alkoxycarbonyl-1-alkyl-4-quinolones with benzophenones also gave adducts reacted at the 2-position of 4-quinolones. On the contrary, the electroreductive coupling of 1,3-diethooxycarbonyl-8-methoxy-4-quinolones occurred at the 4-position of 4-quinolones to give 4-substituted quinolines.

The reversible oxidation of methionine residues in proteins has emerged as a biologically important post‐translational modification. However, detection and quantitation of methionine sulfoxide in proteins is difficult. Our aim is to develop a method for specifically derivatizing methionine sulfoxide residues. We report a Pummerer rearrangement of methionine sulfoxide treated sequentially with trimethylsilyl chloride and then 2‐mercaptoimidazole or pyridine‐2‐thiol to produce a dithioacetal product. This derivative is stable to standard mass spectrometry conditions, and its formation identified oxidized methionine residues. The scope and requirements of dithioacetal formation are reported for methionine sulfoxide and model substrates. The reaction intermediates have been investigated by computational techniques and by 13C NMR spectroscopy. These provide evidence for an α‐chlorinated intermediate. The derivatization allows for detection and quantitation of methionine sulfoxide in proteins by mass spectrometry and potentially by immunochemical methods., Oxidation of methionine residues in proteins is a biologically important post‐translational modification that is difficult to study. We show that activation of sulfoxides with TMSCl generates α‐chloro intermediates, which then react with specific thiols to generate dithioacetals. This modified Pummerer reaction can be used to study methionine sulfoxides in proteins.

Studies on directed ortho-metalation (DoM) of arenesulfonyl fluorides (ArSO2F) with in situ electrophile trapping are presented. Under optimized conditions (LDA, THF, –78 °C), a series of model substrates was mono- and difunctionalized with trimethylsilyl chloride in good yields. The synthetic results reveal powerful directing character of the SO2F group, being ahead of bromine and methoxy substituents. Under the same metalation conditions, aryl fluorosulfates (ArOSO2F) display fragmentation to arynes and migration of the SO2F group to the ortho position (anionic thia-Fries rearrangement).

The reaction of 4,4-dichloro-2,6-di(n-butyl)dithienogermole (DTGCl) with lithium naphthalenide yielded a dark blue solution, which was treated with methyl iodide to provide a 4,4-dimethylated product in 67% isolated yield, indicating the formation of 4,4-dilithio-2,6-di(n-butyl)dithienogermole (DTGLi). Similar treatment of the dark blue solution containing DTGLi with trimethylsilyl fluoride and water gave the corresponding 4,4-disubstituted products. When trimethylsilyl chloride was used, however, no silylated products were obtained, likely due to steric hindrance. The reaction of DTGLi with DTGCl gave poly[2,6-di(n-butyl)dithienogermole-4,4-diyl], whose UV–vis absorption spectra revealed a more extended conjugation than that of a previously prepared product from the Wurtz-type coupling of DTGCl with sodium. Reinvestigation of the electronic states of poly(dithienogermole-4,4-diyl) derivatives on the basis of crystal orbital calculations was also accomplished.

A green and environmentally benign protocol is developed for the synthesis of Schiff bases of sulphur containing compound by irradiating thiazole and pyrazole aldehyde in glycerol under microwave irradiation at 70 ºC with trimethylsilyl chloride (TMSCl) as a catalyst. The method has advantages such as excellent yield, use of green solvent, easy work-up and most important the reaction completed within 2.5 min by using TMSCl catalyst. The TMSCl is an acidic catalyst, which enhances the yield of product, reaction time (with microwave, with reflux at 75 ºC and with stirring at room temperature) which can be easily removed from reaction mask.

We showed for the first time, the fundamental role of CH3CN associated to TMSCl/NaI combination to deprotect S,S-ethylene- and S,S-propylene-ketals into ketones. Indeed, if the TMSCl/NaI association leads to the reduction of dithioketals in CH2Cl2, we have demonstrated that this association can be used to deprotect a large variety of various dithioketals into ketones in CH3CN. Otherwise, under mild experimental conditions, O,O-acetals as well as O,S-oxathianes were cleanly deprotected with high yields. It is also possible to easily regenerate the carbonyl function of various hydrazones and imines using this novel protocol. We believe that this metal-free process is a good alternative to other known methodologies used to deprotect dithioketals into ketones.

Introduction: Quinoxalines show diversified applications in the field of medicinal chemistry. Materials and Methods: Therefore, we have designed a highly efficient, environmentally benign and one-pot protocol for the synthesis of 2-phenylquinoxaline from the reaction of Acetophenone, N-bromosuccinimide and 1,2-phenylenediamine under ultrasound irradiation in glycerol-water. Results and Discussion: We observed that, although the reaction efficiently completed in all of these solvents, the use of glycerol-water with different ratios gives consistently higher yields (89–94%) and decreases reaction times. Conclusion: The main advantages of this protocol are that it is a green method, avoids the use of toxic catalysts and volatile organic medium and the product is obtained with excellent yield.

International audience; Herein we report the use of catalytic amount of scandium(III) triflate or indium(III) chloride (with trimethylsilyl chloride) for the functionalization of endoperoxyacetals through Sakurai or Mukaiyama reactions. These catalysts allow milder and more practical conditions than those previously reported with improvements in scope and reproducibility. This method allows a full catalytic sequence from cyclopropanols to produce desired functionalized 1,2-dioxolanes.

Direct transamidation of secondary amides was developed via nickel catalysis. In the presence of trimethylsilyl chloride and manganese, Ni(diglyme)Cl2 with a Briphos ligand efficiently promoted the transamidation of N-aryl benzamide derivatives with primary amines to afford the corresponding secondary amides in moderate to good yields. Primary amines bearing electron-donating groups gave higher yields of the transamidation products.

An active in situ-generated Nb complex was used as a catalyst in the ring-closing metathesis reaction of N,N-diallyl-p-toluenesulfonamide to afford the corresponding 3-pyrroline derivative. The Nb complex was formed from NbCl5, trimethylsilyl chloride, Zn, and PhCHCl2 in tetrahydrofuran. The Nb complex displayed high catalytic activity toward ring-closing metathesis reactions.

The synthesis of aromatic ketones by chromium-catalyzed Kumada arylation of secondary amides with organomagnesium reagents is described. This reaction was enabled by using low-cost chromium(III) salt as a precatalyst, combined with trimethylsilyl chloride as an additive, and presents a rare example of catalytic transformation of secondary amides to ketones at room temperature. It was shown that catalytically active low-valent chromium species might be responsible for the amide–ketone exchange by mechanism involving the activation of benzimidate intermediate.

Starting from (S,S)-1,1′-bis(4-isopropyloxazolin-2-yl)ferrocene, all possible 2-trimethylsilyl- and 2,2′-di(trimethylsilyl)-substituted diastereoisomers, potential bisoxazoline ligands for use in asymmetric catalysis, were synthesised by selective lithiation followed by addition of trimethylsilyl chloride. Access to the (S,S,R p,R p)-diastereoisomer was achieved following diastereoselective introduction of two deuterium-blocking groups and utilisation of the high k H/k D value for lithiation, methodology that was also applied to the synthesis of a related 2,2′-di(diphenylmethanol)bisoxazoline ligand.

The deoxygenation of tertiary and secondary alcohols to give the corresponding alkanes is conventionally performed using an organosilane and a strong acid. In this study, a deoxygenation method was developed for tertiary and secondary alcohols, using trimethylsilane and trimethylsilyl iodide generated in situ from sodium borohydride and trimethylsilyl chloride, and trimethylsilyl chloride and potassium iodide, respectively. With our method, tertiary and secondary alcohols, which provided stable carbocations, were converted into the corresponding alkanes. This paper also presents the optimization of the reaction conditions, the reaction mechanism, as well as the scope and limitations of the method.

Diastereoselective aldol reaction of N-tert-butanesulfinyl imidates under typical hard enolization conditions is reported. Potassium bis(trimethylsilyl)amide (KHMDS) effectively promotes the aldol reaction of α-aryl- and α-alkyl-substituted imidates, providing anti-aldol adducts in high yields with good to excellent diastereoselectivities. In the case of α-aryl imidates, high conversion depends on adding trimethylsilyl chloride (TMSCl) to the reaction mixture. In the presence of a suitable Lewis acid, cyclohexanone is a good electrophile in the aldol reaction of imidates.

Half-sandwich complexes of the N-heterocyclic carbene-phosphinidene adduct [(IPr)PH] (1, IPr = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) were prepared by its reaction with dimeric complexes of the type [LMCl2]2, which afforded the three-legged piano-stool complexes [LMCl2{HP(IPr)}] (9a/9b: M = Ru/Os, L = η6-p-cymene; 10a/10b: M = Rh/Ir, L = η5-C5Me5). Their conversion into the corresponding carbene-phosphinidenide complexes [LMCl{P(IPr)}] (11a/11b: M = Ru/Os; 12a/12b: M = Rh/Ir) with a two-legged piano stool geometry was studied by NMR spectroscopy in the presence of the strong base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). Alternatively, the complexes 11 and 12 were isolated in high yields from the reactions of the carbene-phosphinidene adduct [(IPr)PTMS] (2) with [LMCl2]2, whereby formation of the metal-phosphorus bonds was accompanied by elimination of trimethylsilyl chloride (Me3SiCl). Theoretical calculations reveal a strong polarization of the phosphorus ligands upon metal complexation, wh...