Novel approach to 6-alkenyl-substituted pyridoxine derivatives based on the Heck reaction

•A new synthetic approach to 6-alkenyl-substituted pyridoxine derivatives based on the Heck reaction was developed.•The optimal Heck reaction conditions catalyzed with a mixture of Pd(OAc)2, (o-Tol)3P and Bu3N as a base were found.•Seven new 6-alkenyl-substituted pyridoxine derivatives were synthesized using the optimized Heck reaction conditions.•Unexpected products were obtained in the Heck reactions with acrylic acid.•Mechanism for the formation of unexpected products due to decarboxylation process is proposed.