Synthetic Applications of Carbohydrate‐derived Donor‐Acceptor Cyclopropanes

V Ganesh, PR Sridhar… - Israel Journal of …, 2016 - Wiley Online Library
Israel Journal of Chemistry, 2016Wiley Online Library
In this account, we elaborate our group's contribution towards understanding the chemistry
of carbohydrate‐derived donor‐acceptor (DA) cyclopropanes. Our work was mainly focused
on the ring opening of these versatile chiral synthons under the influence of Lewis acid
promoters like electrophilic halogen species, TMSOTf, BF3. OEt2, etc. We studied various
modes of ring opening on these DA cyclopropanes, envisaging the access to intriguing
molecular architectures. These modes of reaction of the DA cyclopropanes can be controlled …
Abstract
In this account, we elaborate our group's contribution towards understanding the chemistry of carbohydrate‐derived donor‐acceptor (DA) cyclopropanes. Our work was mainly focused on the ring opening of these versatile chiral synthons under the influence of Lewis acid promoters like electrophilic halogen species, TMSOTf, BF3.OEt2, etc. We studied various modes of ring opening on these DA cyclopropanes, envisaging the access to intriguing molecular architectures. These modes of reaction of the DA cyclopropanes can be controlled by strategically introducing an electron‐withdrawing group (EWG) onto the cyclopropane ring, which could direct the ring cleavage by polarizing the cyclopropane C−C bond. Our studies also revealed that the ring opening is sluggish in the absence of an EWG. Using this concept, we demonstrated the synthesis of various biologically interesting molecular skeletons, viz., glycoamino acids (GAA), GAA nucleotides, α‐levoglucosan amino acid, and septano‐oligosaccharides, with high selectivity. We also applied our understanding to the first stereoselective synthesis of (S)‐(−)‐longianone and confirmed its absolute configuration. Apart from the inherently activated DA cyclopropanes, we introduced the in situ generation of DA cyclopropanes, starting from vinylcyclopropanes (VCPs). The ring‐opening and ring‐expansion chemistry of these easily accessible synthons was studied. The chemistry developed for carbohydrate‐fused cyclopropanes was also applied for carbohydrate‐derived spiro‐cyclopropanes. The Lewis‐acid‐mediated ring opening of spiro‐DA‐cyclopropanes enabled easy access to fused furopyrans and spirolactones.
Wiley Online Library
以上显示的是最相近的搜索结果。 查看全部搜索结果