Iron-catalyzed cross-coupling between C-bromo mannopyranoside derivatives and a vinyl Grignard reagent: toward the synthesis of the C31–C52 fragment of amphidinol 3
A chemo- and diastereoselective iron-catalyzedcross-couplingbetween C-bromo mannopyranoside derivatives and 2-methyl-1-propenylmagnesium bromide was developed. This method was used as the key step for the synthesis of the mirror image of the C31–C40 and C43–C52 fragments of amphidinol 3 (AM3). These syntheses were achieved from a common trans-tetrahydropyran derived from d-mannose.
carbonyl-substituted (arylsulfinyl)methylradicals is presented, based on experimental results and semiempirical calculations. The influence of dipole-dipole interactions, allylic 1,3-strain (A1,3 strain), allylic 1,2-strain (A1,2 strain), and coulombic interactions is discussed based on stereoselectivities observed with (alkoxycarbonyl)-, cyano-, and aryl-substituted (arylsulfinyl)methylradicals. In the second part
Stereoselectivity of the reactions of N-phthaloyl iminium ions and amino-substituted radicals derived from threonine
作者:Philippe Renaud、Aleksandar Stojanovic
DOI:10.1016/0040-4039(96)00387-5
日期:1996.4
Reactions of phthalimido-substituted radicals of type B and iminium ions of type C have been investigated. Similar stereoselectivities were observed in both cases and explained by a model based on minimization of allylic1,3-strain. The first intermolecular radical addition to the a β-substituted dehydroamino acid is reported.
1,5-Induction in reactions of 4-alkoxy-2-trimethylsilylalk-2-enyl(tributyl)stannanes with aldehydes
作者:Nicholas H Taylor、Eric J Thomas
DOI:10.1016/s0040-4020(99)00442-1
日期:1999.7
2-Trimethylsilylalk-2-enylstannanes undergo tin(IV) chloride promoted reactions with aldehydes to give homoallylic alcohols with retention of the 2-trimethylsilyl group. 4-Alkoxy-2-trimethylsilylalk-2-enyl(tributyl)stannane 31 reacts with aldehydes under these conditions with excellent stereoselectivity in favour of the 1,5-syn-(E)-products 32 – 35. Preliminary studies into the chemistry of these vinylsilanes
Diastereoselective radical mediated alkylation of a chiral glycolic acid derivative
作者:Sokol Abazi、Liliana Parra Rapado、Philippe Renaud
DOI:10.1039/c1ob05230f
日期:——
Radical alkylation of 2-(tert-butyl)-2-methyldioxolan-4-one, a chiral equivalent of glycolic acid, occurs with good to high diastereoselectivity that compares favorably with the corresponding enolate alkylation. The importance of the position of the transition state position, early or late, is highlighted.