Functional monomers and polymers, 92. Synthetic application of the dehydrating and desulfhydrylating activity of chloropyrimidine derivatives, particularly of the immobilized derivative

Chloropyrimidine derivatives were found to be useful as active dehydrating and desulfhydrylating reagents for the preparation of carbodiimides, isothiocyanates, esters, lactones, amides, or nitriles. Particularly a polystyrene‐bound reagent was quite useful also due to the advantage of isolating the products easily by using a simple filtration technique. The following decreasing order of reactivity was found: 4‐chloro‐2‐pyrimidone bound to polystyrene (poly{1‐[4‐(4‐chloro‐2‐oxo‐1,2‐dihydro‐1‐pyrimidinyl)phenyl]ethylene}) ( 5a ) ≃ 4‐chloro‐1‐cyclohexyl‐2‐pyrimidone ( 3a ) > 2,4,6‐trichloropyrimidine ( 2a ) > 2,4‐dichloropyrimidine ( 1a ) ≫ 9‐benzyl‐6‐chloropurine ( 4a ). The reactivities are related to the structure, and an enhanced ease of lactim‐lactam tautomerism in the products is suggested as driving force of the reaction.