Application of the Ibuka-Yamamoto reaction to a problem in stereochemical communication: a strategy for the stereospecific synthesis and stabilization of the triene substructure of rapamycin through sulfone substitution
摘要:
The aldehydes 49 and 55 corresponding to carbons 13-30 in a projected total synthesis of rapamycin have been synthesized. The LACDAC technology was used to elaborate dithiane enal 5. The aldehyde 4 was synthesized from D-(+)-glucose. A critical element of that construction involved cuprate-induced displacement reactions on enoates 7 and 8 (see formation of esters 9a and 9b) to correlate the stereochemistry of carbons 8 and 12. The feasibility of conducting a Nozaki-Kishi reaction between iodosulfone 6 and aldehyde 4 was a major simplification. Julia coupling between sulfone 5 and aldehyde 43 was followed by acetylation and elimination of acetic acid. The triene sulfone 54 was obtained stereospecifically. The C4 sulfone linkage is a considerable stabilizing element on the C1-C6 triene. Its presence allows for removal of the dithiane linkage (see formation of aldehyde 55). Cleavage of the sulfone is accomplished with sodium analgam without reduction of an aldehyde function at C30 (see formation of 49).
Application of the Ibuka-Yamamoto reaction to a problem in stereochemical communication: a strategy for the stereospecific synthesis and stabilization of the triene substructure of rapamycin through sulfone substitution
作者:Sui Hui Chen、Raymond F. Horvath、Jesus Joglar、Matthew J. Fisher、Samuel J. Danishefsky
DOI:10.1021/jo00020a027
日期:1991.9
The aldehydes 49 and 55 corresponding to carbons 13-30 in a projected total synthesis of rapamycin have been synthesized. The LACDAC technology was used to elaborate dithiane enal 5. The aldehyde 4 was synthesized from D-(+)-glucose. A critical element of that construction involved cuprate-induced displacement reactions on enoates 7 and 8 (see formation of esters 9a and 9b) to correlate the stereochemistry of carbons 8 and 12. The feasibility of conducting a Nozaki-Kishi reaction between iodosulfone 6 and aldehyde 4 was a major simplification. Julia coupling between sulfone 5 and aldehyde 43 was followed by acetylation and elimination of acetic acid. The triene sulfone 54 was obtained stereospecifically. The C4 sulfone linkage is a considerable stabilizing element on the C1-C6 triene. Its presence allows for removal of the dithiane linkage (see formation of aldehyde 55). Cleavage of the sulfone is accomplished with sodium analgam without reduction of an aldehyde function at C30 (see formation of 49).