Procedure for preparing derivatives of pyrano- 2,3-c pyridine

摘要

A method comprising the step of dehydrating a compound of Formula (I): ** Formula ** with a suitable dehydrating reagent to form a compound of Formula (II): ** Formula ** wherein R1 is -CH = CH -R8 or -CH2-CH = CH-R9; R2 is C1-C4 alkyl; R3 is H, C1-C4 alkyl, benzyl, -phenyl- (R10) x, or -C1-C4-alkyl-COO-C1-C4-alkyl; each R4 is independently H, or C1-C4 alkyl; each R5 and each R6 are independently H, C1-C4-alkyl, -O-C1-C4-alkyl, or -S-C1-C4-alkyl; R7 is R8 or -CH2-R9; R8 is H, C1-C4-alkyl, -phenyl- (R10) x, or -COO-C1-C4-alkyl; R9 is H, C1-C3 alkyl, -phenyl- (R10) x, or -COO-C1-C4 alkyl; each R10 is independently halo, C1-C4-alkyl, -O-C1-C4-alkyl, or -S-C1-C4-alkyl; and each x is independently 0, 1 or 2.