204381-45-3Relevant academic research and scientific papers
Total synthesis of spinosyn A. 2. Degradation studies involving the pure factor and its complete reconstitution
Paquette, Leo A.,Collado, Iván,Purdie, Mark
, p. 2553 - 2562 (2007/10/03)
A total synthesis of natural levorotatory spinosyn A (1) has been achieved. The first objective, to confirm the absolute configurational assignment of tricyclic ketone 2 prepared earlier, was accomplished by oxidative degradation of the macrocyclic lactone ring in 1. The route began with the implementation of a four-step one-pot process that resulted in the efficient conversion of 6 into 18. A combination of periodate cleavage and peracid oxidation events then led to 2. In the reconstruction phase, a Pd- catalyzed coupling of a vinylstannane with an acid chloride reestablished the great majority of the structure in an enantiocontrolled manner. Once macrolactonization had been effected, the 2,3,4-tri-O-methylrhamnose unit was introduced first with exceptionally good stereocontrol. The final glycosidation, which involved a 2-mercaptopyrimidine derivative of D- forosamine, was met with an expectedly diminished percentage of the desired β-anomer.
