Simple and effective synthesis of pyrido[2,1-b]thiazines
Abstract
One-step annelation of the 1,3-thiazine derivatives (1, R1= h) is achieved using substituted acrylic acids under peptide coupling conditions; use of sterically hindered acrylic acids results in an anomalous reaction and the thiazine derivative (1, R1= R2= Et) gives an interesting rearrangement.