Reaction of Allylic Tin Reagents with Nitrogen Heteroaromatics Activated by Alkyl Chloroformates: Regioselective Synthesis of α-Allylated 1,2-Dihydropyridines and Change of the Regioselectivity Depending on Methyl Substituents at the Allylic Moiety

Article abstract of DOI:10.1021/jo00250a018

Allyltin reagents readily react with pyridine and some substituted pyridines activated by alkyl chloroformates to give α-allylated 1,2-dihydropyridines regioselectively.Functional substituents such as halogeno, acetoxy, and formyl groups can be tolerated, demonstrating high chemoselectivity of the reactions.The regiochemistry of the attack on pyridine nuclei changes from α-addition to α- and γ-addition (nonregioselective) to γ-addition, depending on methyl substituents at the allylic moiety (from allyl to methallyl and crotyl to prenyl groups).It is also found that the reactions occur at the γ-position of allylic tin reagents, indicating S_N2' character of the reactions.The present effective allylation method can be extended to isoquinoline and quinoline systems.