Unusual anionic desalting oligomerization of alkali metal salts of bromo-substituted bicyclic oxalactam

Abstract

2797calorimetry curves of samples and components, and X-ray diffraction scan of sample I1 component 1 (29 pages). Ordering information is given on any current masthead page. In this paper the periodic group notation in parentheses is in accord with recent actions by IUPAC and ACS nomenclature committees. A and B notation is eliminated because of wide confusion. Groups IA and IIA become groups 1 and 2. The d-transition elements comprise groups 3 through 12, and the p-block elements comprise groups 13-18: (Note that the former Roman number designation is preserved in the last digit of the new numbering: e.g., I11 -3 and 13.)ABSTRACT The oligomerization of sodium and potassium salts of a new bromo-substituted bicyclic oxalactam, 4(e)-bromo-8-oxa-6-aabicyclo[3.2.l]odan-7-one (I), proceeds in Nfl-dimethylformamide or dimethyl sulfoxideat 0 or 25 "C with elimination of alkali metal bromide to give novel oligomers 2 having a bicyclic oxalactam ring in each monomer unit. Oligomers similarly obtained from mixtures of 1 with its sodium salt had lower average molecular weight. Two diastereomeric dimers and a trimer were isolated by fractional elution from a preparative silica gel column. Structural analyses indicate that the oligomerization proceeds with high enantiomeric selectivity and complete retention of the configuration of the bridgehead methine carbon atom adjacent to nitrogen. Possible mechanisms for this oligomerization are presented.