Application of pyrrolo-protected amino aldehydes in the stereoselective synthesis of -1,2-amino alcohols.

Herein, we demonstrate the applicability of the 2,5-dimethylpyrrolo unit as a complementary -protecting group in the highly diastereoselective synthesis of more than 20 different -amino alcohols (63-90% yields with up to 20 : 1 dr). Cleavage of the pyrrolo--protecting group was accomplished, in the presence of NHOH under microwave conditions with yields exceeding 80%. The applicability of the protecting groups was further demonstrated by a short total synthesis of the sphinganine-like natural product clavaminol A. The introduction of the -pyrrolo protecting group also offers the possibility to analyse product mixtures by NMR measurements due to the absence of conformational isomers, which are otherwise common for -protecting groups.