Hydroxyl-Directed Stereoselective Diboration of Alkenes
作者:Thomas P. Blaisdell、Thomas C. Caya、Liang Zhang、Amparo Sanz-Marco、James P. Morken
DOI:10.1021/ja504228p
日期:2014.7.2
An alkoxide-catalyzed directed diboration of alkenyl alcohols is described. This reaction occurs in a stereoselective fashion and is demonstrated with cyclic and acyclichomoallylic and bishomoallylic alcohol substrates. After oxidation, the reaction generates 1,2-diols such that the process represents a method for the stereoselective directed dihydroxylation of alkenes.
Diastereoselective construction of cis 2,6-disubstituted tetrahydropyran rings via In(OTf)3-catalyzed intramolecular 2,5-oxonium-ene cyclization: synthetic studies towards the total synthesis of zampanolide and dactylolide
Diastereoselective construction of 2,6-disubstituted tetrahydropyrans with an exocyclic double bond was achieved via the In(OTf)3-catalyzed intramolecular 2,5-oxonium-ene cyclization. Its application was further demonstrated by the synthesis of a common intermediate for both zampanolide and dactylolide, fragment I, with a total yield of 42% in three steps starting from (2E)-3-bromobut-2-enal.
Scandium-Catalyzed Allylboration of Aldehydes as a Practical Method for Highly Diastereo- and Enantioselective Construction of Homoallylic Alcohols
作者:Hugo Lachance、Xiaosong Lu、Michel Gravel、Dennis G. Hall
DOI:10.1021/ja036807j
日期:2003.8.1
A general approach for the allylation of aldehydes using stable, air-tolerant camphor-based chiralallylboronates under Sc(OTf)3 catalysis is described. This practical methodology provides both syn and anti propionate units and other homoallylic alcohols with very high levels of diastereo- and enantioselectivity for several substrates, including functionalized aliphatic aldehydes useful toward the