α-(Disilylallenyl) α-amino acid derivatives from the Claisen rearrangement of propargyl glycinates

Silylpropargyl glycinate esters undergo [3,3]-sigmatropic rearrangements to give 2-(disilylallenyl)glycine derivatives, interesting highly functional synthons, in moderate to good yield (30 to 85%) and in high diastereoselectivity when directed by a large silylpropargyl group (9:1 to 22:1). The highly functional amino acid, methyl ( R )-2-(Boc-amino)-3,5-bis(trimethylsilyl)hexa-3,4-dienoate was isolated and characterized by X-ray crystal structure analysis.