Stereochemistry of diamination of (E)- and (Z)-2-butenes: Crystal and molecular structures of meso- and dl-2,3-diaminobutane ditosylates

Abstract

Stereospecific anti-addition of diethyl N,N-dibromophosphoramidate (DBPA) to (E)- and (Z)-2-butenes was definitely corroborated by X-ray structural determinations ofthreo- anderythro-2-amino-3-bromobutane hydrochlorides prepared from the corresponding adducts without changing the configuration on either chiral centers. The stereochemistry of azidation ofthreo- anderythro-2-amino-3-bromobutane hydrochlorides leading todl- andmeso-2,3-diaminobutane ditosylates respectively (after reduction of an azide function) was deduced from an X-ray crystallographic analysis of these diamine salts. The X-ray crystallographic analysis was carried out for three compounds: two reaction products and substrate (Scheme 2).