Synthesis of enantiopure 1-alkoxyallenes and their 3-alkylated derivatives

A series of enantiopure 1-allcoxyallenes la-lf was prepared starting from p ropargyl bromide and the corresponding optically active alcohols via propar gyl ethers 3a-3f as intermediates. In addition, disubstituted enantiopure a llene derivatives 5a-5c were synthesized by isomerization of the correspond ing alkynes 4a-4c. Allene derivative 5a was also prepared via an alternativ e route with 1-trimethylsilylallene derivative 6a as crucial intermediate.