中文名称 | 英文名称 | CAS号 | 化学式 | 分子量 |
---|---|---|---|---|
—— | (6aR,10R,10aS)-10-phenylmethoxy-2,2,4,4-tetra(propan-2-yl)-6,6a,10,10a-tetrahydropyrano[3,2-f][1,3,5,2,4]trioxadisilocine | 244770-77-2 | C25H42O5Si2 | 478.776 |
—— | (6aR,8S,9S,10R,10aR)-10-phenylmethoxy-2,2,4,4-tetra(propan-2-yl)-9-prop-2-enoxy-8-prop-2-enyl-6,6a,8,9,10,10a-hexahydropyrano[3,2-f][1,3,5,2,4]trioxadisilocine | 244770-80-7 | C31H52O6Si2 | 576.921 |
—— | (1R,3S,9S,10R,11R)-10-phenylmethoxy-13,13,15,15-tetra(propan-2-yl)-2,8,12,14,16-pentaoxa-13,15-disilatricyclo[9.6.0.03,9]heptadec-5-ene | 244770-82-9 | C29H48O6Si2 | 548.868 |
The utility of unconventional noncovalent interactions (NCIs) such as chalcogen bonding has lately emerged as a robust platform to access synthetically difficult glycosides stereoselectively. Herein, we disclose the versatility of a phosphonochalcogenide (PCH) catalyst to facilitate access into the challenging, but biologically interesting 7‐membered ring α,α’‐C‐disubstituted oxepane core through an α‐selective strain‐release C‐glycosylation. Methodically, this strategy represents a switch from more common but entropically less desired macrocyclizations to a thermodynamically favored ring‐expansion approach. In light of the general lack of stereoselective methods to access C‐septanosides, a remarkable palette of silyl‐based nucleophiles can be reliably employed in our method. This include a broad variety of useful synthons, such as easily available silyl‐allyl, silyl‐enol ether, silyl‐ketene acetal, vinylogous silyl‐ketene acetal, silyl‐alkyne and silylazide reagents. Mechanistic investigations suggest that a mechanistic shift towards an intramolecular aglycone transposition involving a pentacoordinate silicon intermediate is likely responsible in steering the stereoselectivity.