The reaction of the title carbanions with several aldehydes and ketones to afford the corresponding ketene dithioketals was studied. It was found that the P O organolithium reagent reacted with both types of carbonyl substrates in good to excellent yields. On the other hand, the P S reagent reacted selectively with aldehydes although in poor yield. This contrasting behavior can not be ascribed to a greater stability of the latter carbanion since ...