α-Trialkylsilyl-Substitutedα-Amino Acids

New unsaturated amino acids containing an allylsilane moiety on the lateral chain

“…1 H NMR spectra were recorded at 200 or 400 MHz. 13 Starting materials 1 and 7 were prepared according to the literature. 18,26 THF was dried by distillation over sodium benzophenone ketyl.…”

“…4 More recently, silaproline has been found to lend unique properties to neurotensin analogues. 5 Some examples of silylated amino acids have been reported in the literature so far, such as b-silylamino acids, [6][7][8] p-substituted phenylananine, 9 silaproline, 10,11 and a-silyl amino acids, which have been prepared both in racemic 12,13 and in the enantiomerically enriched forms. 14,15 Recently we have been able to prepare some enantiomerically enriched new silicon-containing amino acids starting from enantiomerically pure oxazolidine 1, a compound we synthesized for the first time some years ago, [16][17][18] which can be obtained on multigram scales from naturally occurring serine.…”

Straightforward Synthesis of Chiral Silylated Amino Acids through Hydrosilylation

“…A four‐step enantioselective synthesis of γ‐silylated amino acids was reported by using a procedure based on silylcupration of amino alcohols followed by oxidation into amino acids 17,18. An amino acid in which the silicon was attached directly to the α carbon has also been prepared as a racemate by a rhodium‐catalysed reaction 19. A single enantiomer was obtained by using an asymmetric reverse‐aza‐Brook rearrangement 20.…”

Synthesis and applications of silicon-containing α-amino acids

“…An efficient, catalytic method for the production of a-trialkylsilyl amino acids is the Rh-catalysed N-H insertion of tosylamide, tert-butoxy carbamate or carbobenzyloxy carbamate into trialkylsilyl diazo esters 5 (Table 1). 7 These starting materials are easily prepared from diazo acetates and silyl triflates or chlorides and dirhodium tetraacetate as catalyst (2 mol%). With this route racemates are obtained, and unfortunately no chiral catalyst has yet been found to effect the reaction.…”

“…Catalytic hydrogenation of the separated enantiomers of 1i results in complete deprotection affording free amino acids (+)-4 and (À)-4 in enantiopure form. 7 Related strategies can be applied for the synthesis of a-trialkylsilyl hydroxy acids 6. [8][9][10] There, rhodium-catalysed O-H insertions, carbonyl reductions of keto esters 7 or alkyne oxidations are used for the preparation of protected derivatives.…”