An Efficient Method to Construct the A,B-Rings Component toward Total Syntheses of Phycocyanobilin and Its Derivative as a Photoprobe

摘要

Total syntheses of phycocyanobilin and its derivative bearing a photoreactive group at the D-ring were accomplished by developing a new and efficient method for the construction of A,B-rings component,which consists of the Wittig-type new coupling reaction of 4-(1-methoxyethyl or 1-tosylethyl)-3methyl-5-tosyl-1,5-dihydro-2H-pyrrol-2-one and a 2-formyl pyrrole derivative in the presence of ~nBu_3P and a base,followed by reduction with aluminum analgam and a subsequent acid or base treatment.