The conversion of aldehydes and ketones to the corresponding gem-dichlorides is a very important transformation in organic synthesis because these compounds can serve as precursors to transition-metal alkylidenes for carbonyl olefination [ 1 1. (a) Piotrowski , AM ; Malpass , DB ; Boleslawski , MP ; Eisch , JJ Alkylenation with geminal dialuminoalkane reagents: The synthesis of olefins from ketones . J. Org. Chem. 1988 , 53 , 2829 – 2835 ; (b) Takai , K. ; Shinomiya ...