Reaction of dichlorocarbene with 2,2,4-trimethyl-1,2-dihydroquinoline and its derivatives

1. The reaction of dichlorocarbene with 6-R-2,2,4-trimethyl-1,2-dihydroquinolines gives formylation at the N-H bond followed by [1+2] cycloaddition at the double bond with formation of the corresponding 7-R-1-formyl-2,2,5-trimethyl-4,4-dichlorocyclopropane[c]-quinolines. 2. The yields of the [1+2] cycloaddition products decreases with increasing nucleophilicity of the nitrogen atom in the dihydroquinoline ring.