Enantioselective synthesis of cyclopropane aminoalcohols containing quaternary stereogenic centers

Some title compounds have been synthesized in enantiomerically pure form st arting from D- or L-glyceraldehyde as chiral precursors. A new synthesis of (+)-(Z)-methanohomoserine, one of the key intermediates employed, is also described. The target molecules are densely functionalized. Thus, in additi on to one or two hydroxyl groups on a side-chain, an amino group is attache d to a quaternary carbon of the cyclopropane ring, and the fourth substitue nt of such a stereogenic center contains a halogen atom, an alkyl group, or an alcohol, thioether or ester function. Some of these compounds are usefu l precursors in the synthesis of new cyclopropane nucleosides. (C) 1999 Els evier Science Ltd. All rights reserved.