TY - JOUR
T1 - 1,3-Dipolar cycloadditions of diazomethane to chiral electron-deficient olefins: The origin of the π-facial diastereoselection
AU - Muray, Elena
AU - Alvarez-Larena, Angel
AU - Piniella, Joan F.
AU - Branchadell, Vicenç
AU - Ortuño, Rosa M.
PY - 2000/1/28
Y1 - 2000/1/28
N2 - The stereochemical outcome of diazomethane cycloadditions to several chiral electron-deficient olefins has been investigated in order to establish the origin of the π-facial diastereoselection. Nitro olefins, vinyl sulfones, enoates, and 2-amino enoates have been used for such a purpose. These substrates have been prepared from D-glyceraldehyde acetonide through Wittig-type condensations and present an alkoxy substituent, provided by the bulky dioxolane ring, attached to the stereogenic allylic carbon. Syn-adducts have been obtained in all cases as the major isomers, independently of the Z/E stereochemistry of the double bond and the number and the nature of the substituents, the chirality of the asymmetric allylic carbon being the only thing responsible for the diastereoselection. Theoretical calculations show that steric hindrance due to the bulky dioxolane group is the main factor governing the preference for the syn-attack of diazomethane to the olefinic double bond.
AB - The stereochemical outcome of diazomethane cycloadditions to several chiral electron-deficient olefins has been investigated in order to establish the origin of the π-facial diastereoselection. Nitro olefins, vinyl sulfones, enoates, and 2-amino enoates have been used for such a purpose. These substrates have been prepared from D-glyceraldehyde acetonide through Wittig-type condensations and present an alkoxy substituent, provided by the bulky dioxolane ring, attached to the stereogenic allylic carbon. Syn-adducts have been obtained in all cases as the major isomers, independently of the Z/E stereochemistry of the double bond and the number and the nature of the substituents, the chirality of the asymmetric allylic carbon being the only thing responsible for the diastereoselection. Theoretical calculations show that steric hindrance due to the bulky dioxolane group is the main factor governing the preference for the syn-attack of diazomethane to the olefinic double bond.
U2 - 10.1021/jo991227j
DO - 10.1021/jo991227j
M3 - Article
VL - 65
SP - 388
EP - 396
IS - 2
ER -