R4 each are ##STR2## R2, R3, R5, R6, R7 and R8 each are an alkyl group having 1 to 10 carbon atoms;...http://www.google.com/patents/US4478953?utm_source=gb-gplus-sharePatent US4478953 - Polymerization process of optically active polymer and catalyst thereforAdvanced Patent SearchPublication numberUS4478953 APublication typeGrantApplication numberUS 06/471,584Publication dateOct 23, 1984Filing dat