Synthesis of fluorinated allylic amines: Reaction of 2-(trimethylsilyl)ethyl sulfones and sulfoxides with fluorinated imines

A new synthesis of fluorinated allylamines through the reaction of 2-(trimethylsilyl)ethyl sulfones and sulfoxides (as vinyl anion equivalents) with imines and imino esters has been described. The process includes a TBAF-mediated fragmentation of 2-(trimethylsilyl)ethyl sulfones to afford the desired allylic amines. When the reaction is performed with the corresponding sulfoxides, the fragmentation takes place under the addition conditions, affording the final products in a single step.     

Preparation of optically pure propargylic and allylic alcohols from 2-(trimethylsilyl)vinyl sulfoxides as a chiral ethynyl anion synthon: computational studies on elimination reaction of 2-(trimethylsilyl)vinyl sulfoxides

The reaction of the alpha-carbanion derived from (trimethylsilyl)vinyl sulfoxides with aldehydes afforded a diastereomeric mixture of the products. Each diastereomer was subjected to specific elimination reactions to give optically pure propargylic, trimethylsilylated propargylic, and allylic alcohols. Acceleration of the sulfenic acid-elimination from the beta-silylvinyl sulfoxide was demonstrated by the ab initio calculation to be ascribed mainly to the beta-effect of the silyl group.     

Application of substituted 2-(trimethylsilyl)ethyl esters to suppress diketopiperazine formation

The use of differently substituted 2-(trimethylsilyl)ethyl esters for C-terminal protection in peptide synthesis has been investigated. While the use of the unsubstituted 2-(trimethylsilyl)ethyl ester resulted in a substantial amount of diketopiperazine at the dipeptide stage, use of the corresponding methyl-substituted silyl ester gave a significant reduction of this undesired pathway. Both esters could be deprotected by fluoride-induced cleavage under mild conditions.     

Synthesis and NMR elucidation of four novel 2-(trimethylsilyl)ethyl glycosides

Four novel 2-(trimethylsilyl)ethyl glycosides have been synthesized by a short and efficient route starting from d-glucose. Their structures were elucidated by applying high-resolution mass spectra, and one-dimensional and two-dimensional NMR techniques. These glycosides were prepared and used as intermediate building blocks in the scheme developed for oligosaccharide construction.     

Selective formal transesterification of fluorinated 2-(trimethylsilyl)ethyl alpha-imino esters mediated by TBAF

The scope of the transesterification reaction between beta-fluorinated alpha-imino esters and various electrophiles in the presence of TBAF as fluorine source is described. The reaction is highly selective for alkyl iodides, bromides, and mesylates, while alkyl chlorides react at a significantly slower rate and tosylates do not react under the reaction conditions. This methodology represents a simple and useful alternative for the preparation of a wide variety of fluorinated alpha-imino esters.     

Base-catalyzed homo-brook rearrangement of diastereomeric 7,8- epoxy-7(trimethylsilyl)-6-tridecanols

Semi-quantitative rate measurement of base-catalyzed 1,3-migration of a silyl group from carbon to oxygen (homo-Brook rearrangement) using four diastereomerically pure title compounds revealed that the aptitude for the migration depends markedly on the configurational environment around the trimethylsilyl group of the respective substrate.     

Synthesis of 2-(trimethylsilyl)-1,3-butadienes

The reactions of trimethylsilyl-substituted α-allenic alcohols with lithium aluminum hydride afforded 2-(trimethylsilyl)-1,3-butadienes.     

N-Polyfluoro(trimethylsilyl)ethyl azole derivatives

A facile synthetic route to N-polyfluoro(trimethylsilyl)ethyl azole derivatives was developed starting from N-bromo(chloro)polyfluoroethyl-substituted azoles. The silanes thus obtained were reacted with various electrophiles in the presence of the fluoride ion to yield the corresponding fluorinated carbinols, ketones, carboxylic acids, and methyl dithiocarboxylates as well as N-pentafluoroethylbenzimidazole.     

Theoretical Analysis of the Reactivity of N-[2-Bromo-2-(trimethylsilyl)ethyl]sulfonamides and Their Self-Association

Russian Journal of General Chemistry - A theoretical analysis of the reasons for the previously shown experimentally different reactivity of [2-bromo-2-(trimethylsilyl)ethyl]sulfonamides in...     

Metal catalysed Brooke rearrangement of 3-Halo-1-(trimethylsilyl) propan-2-one (Halo = Cl or Br)

The complexes [IrH(CO)(PPh₃)₃], trans-[IrCI(CO)- (PPh₃)₂], [RhH(PPh₃)₄], [Pd(PPh₃)₄], [Pt(trans-stilbene)(PPh₃)₂] and [Pt(η³-CH₂-COCH₂)-(PPh₃)₂] catalyse the rearrangement of Me₃SiCH₂C(O)CH₂Cl to CH₂?C(OSiMe₃)-CH₂Cl.     

Stereoselective synthesis of 2-(2′-cycloalkenyl)glycinates via ester-enolate claisen rearrangement

Ester-enolate Claisen rearrangement of 2-cycloalkenyl N-$\text{t}$-Boc-glycinates leads to the biologically active RS,SR-diastereomers selectively.     

Synthesis of novel selenapenams, selenacephems, and selenazepines using a 2-(trimethylsilyl)ethyl protection approach

Selenapenams, selenacephems, and selenazepines were synthesized using a 2-(trimethylsilyl)ethyl (TSE) protection approach in an extremely simple way. TSE protection for selenium is used for the first time in the synthesis of selenium-containing beta-lactam. Novel intramolecular cycloaddition reaction of selenium with alkynes and allenes is used in the present synthesis.     

1-Phenylthio-1-(trimethylsiloxy)cyclopropanes via the sila-Pummerer rearrangement

This first study of the sila-Pummerer rearrangement in a cyclopropane system reveals that several 1-trimethylsiloxy-1 -(phenylthio)cyclopropanes can be prepared stereoselectively through putative sulfur-stabilized carbocationic intermediates.     

Direct preparation of nucleoside vinyl disulfides from 2-(trimethylsilyl)ethyl sulfides, an access to vinylthiols

We report here a straightforward preparation of various nucleoside vinyl disulfides in high yields under mild conditions using the new reaction of vinyl 2-(trimethylsilyl)ethyl (TMSE) sulfides with sulfenyl chlorides. This reaction allows the preparation of various mixed disulfides from stable silyl sulfides without formation of oxidizable and/or unstable thiols. The easy preparation of vinyl disulfides through this reaction should offer new perspectives in vinylthiol chemistry.     

3-Aminopyrrolidines via ring rearrangement of 2-aminomethylazetidines. Synthesis of (-)-absouline

[reaction: see text] A new entry to enantiopure 3-aminopyrrolidines was developed using a boron trifluoride-mediated rearrangement of 2-aminomethylazetidines. The method is quite general and produces rearranged products in good yield regardless of both substitution pattern and relative stereochemistry of the starting material. A concise stereocontrolled synthesis of (-)-absouline was achieved on the basis of this new method.     

A concise synthesis of turneforcidine via a metalloiminium ion cyclization terminated by the 2-(methylthio)-3-(trimethylsilyl)-1-propenyl moiety

A concise synthetic route to racemic turneforcidine (1) is described that relies on the stereocontrolled cyclization of the 2-(methylthio)-3-(trimethylsilyl)-1-propenyl bearing imine 5 in the presence of TiCl(4). Reaction: see text.     

2-(Trialkoxysilylalkylthio)ethyl vinyl sulfides

Conclusions Trialkoxysilylalkanethiols (CH₃O)₃Si(CH₂)_nSH (n=1–3) react with divinyl sulfide at 100–110° to give 2-(trialkoxysilylalkylthio)ethyl vinyl sulfides (CH₃O)₃Si(CH₂)_nS (CH₂)₂SCH=CH₂ in high yield. The reactivity of the trialkoxysilylalkanethiols decreases with increase in the number of CH₂ groups between the S and Si atoms. A second molecule of the organosilicon thiol acids adds with difficulty to divinyl sulfide to give the diadduct.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 197–199, January, 1977.