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