Preparation of Trimethylsilylmethyl Derivatives Using Phase Transfer Methods

An efficient one-pot protocol for the synthesis of phenyl substituted 3-silatetrahydropyrans

“…That a replacement of bromine for chlorine in 1a does occur was proved by an independent experiment. Refluxing an equimolar mixture of ClCH 2 SiMe 3 and nBu 4 NBr in benzene for 10 h gave a 4:1 mixture of chloro-and bromo compounds whose 1 H NMR data are consistent with the reported ones 27. An attempt to obtain pure bromo derivative 1a-Br by heating the equimolar mixture of 1a and n-Bu 4 NBr gave a mixture of two haloalcohols 1a and 1a-Br (inseparable by column chromatography, from 1 H NMR data) and heterocycle 2a isolated by column chromatography in 29% yield…”

Sommelet–Hauser or Stevens rearrangement of 1-methyl-2-(substituted-phenyl)piperazinium 1-methylides. Ring enlargement of piperazines to seven- or nine-membered cyclic amines

“…Tomoko Kitano, Naohiro Shirai, Manami Motoi and Yoshiro Sato" Faculty of Pharmaceutical Sciences, Nag0 ya City University, Tanabe-dori, Mizuho-ku, Nag0 ya 467, Japan Fluoride ion-induced desilylation of 4-acetyl-l-methyl-2-(4-substituted phenyl) -1 -trimethylsilylmethylpiperazinium iodides 5 gave 5-acetyl-2-methyl-1 O-substituted 1,3,4,5,6,11 a-hexahydro-2H-2,5-benzodiazonines 7 and/or 5-acetyl-2-met hyl-1 0-su bstituted 2,3,4,5,6,7 hexa hydro-1 H-2,5benzodiazonines 8 (Sommelet-Hauser rearrangement products). However, a similar treatment of 1 -methyl -3 -ox0 -2-phenyl-1trimethylsilylmet hyl pi perazi nium iodide 1 0 afforded 1 -methyl -6phenyl-2,3,6,7-tetrahydro-1 H-diazepine-5-one 12 (Stevens rearrangement product).…”

Chiral Carbanions, Part 4:Borylation of (Trimethylsilyl)methylN,N-Dialkylcarbamates - Diastereoselectivity and Structural Studies

“…Three (trimethylsilyl)methyl carbamates, 4a and (R,R)and (S,S)-4b derived from C 2 symmetric amines 6 (R,R)and (S,S)-5 (>99% ee), were prepared to study the diastereoselectivity of borylation (Scheme 1). Carbamate 4a was formed by esterification of trimethylsilylmethanol 7 (2) with commercially available carbamoyl chloride 3 in 81% yield. 8 The amines (R,R)-and (S,S)-5 were first transformed into the intermediate carbamoyl chlorides using trichloromethyl chloroformate, which were converted in situ to the (trimethylsilyl)methyl esters (R,R)-and (S,S)-4b in 87% and 82% yield, respectively.…”

“…8 The amines (R,R)-and (S,S)-5 were first transformed into the intermediate carbamoyl chlorides using trichloromethyl chloroformate, which were converted in situ to the (trimethylsilyl)methyl esters (R,R)-and (S,S)-4b in 87% and 82% yield, respectively. The (trimethylsilyl)methanol was obtained by a modified literature procedure 7 in two steps from (chloromethyl)(trimethyl)silane. Nucleophilic substitution of chloride for acetate in dry DMF with NaOAc and a substoichiometric amount of NaI at 100°C for 24 hours gave the (trimethylsilyl)methyl acetate in 76% yield (see experimental part), which was reduced with LiAlH 4 .…”