ChemInform Abstract: A Highly Stereoselective Approach to the Synthesis of Functionalized Pyran Derivatives by Lewis Acid Assisted Ketal Reduction and Allylation

Autor:	Suzanne Bogaczyk, Philip DeShong, Marc-Raleigh Brescia, Yvonne C. Shimshock
Rok vydání:	2010
Předmět:	chemistry.chemical_compound Stereospecificity chemistry Bicyclic molecule Pyran organic chemicals Diol Organic chemistry Stereoselectivity General Medicine Lewis acids and bases Alkylation Selectivity
Zdroj:	ChemInform. 32
ISSN:	1522-2667 0931-7597
Popis:	Reduction of bicyclic ketal 1 gave functionalized pyran derivatives 7a or 7b in a highly stereoselective manner, depending upon the reduction conditions utilized. For example, treatment of ketal 1 with TiCl4/Et3SiH produced exclusively diol 7b with the 2,5-syn relationship in good yield. Alternatively, reduction of ketal 1 by DIBALH gave 2,5-anti-diol 7a stereoselectively. Alane reductions of ketal 1 were highly stereoselective also; however, the syn/anti selectivity observed was strongly dependent on the ratio of reagents employed for in situ generation of the alane. Lewis acid catalyzed allylation of ketal 1 gave pyran 10 in a stereospecific alkylation reaction.
Databáze:	OpenAIRE
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