Carboazidation of chiral allylsilanes: experimental and theoretical investigations.
The carboazidation of chiral allylsilanes has been investigated by varying the nature of the substituents at the silicon center and on the carbon framework. The influence of temperature and the nature of the sulfonyl azide, as well as the stereochemistry of the remote stereogenic center, on the 1,2-diastereocontrol of the process were considered. Good to excellent levels of diastereocontrol were generally observed, with the syn-beta-azidosilane always being formed as the major isomer. An illustration of the value of this methodology has been provided with a short and efficient synthesis of an analogue of castanospermine. EPR spectroscopy was carried out on various beta-silyl radicals providing useful information about their conformations in the ground state. Based on this experimental evidence and DFT calculations, reactant-like transition state models were finally proposed that rationalize the observed 1,2-stereoinduction.
Chabaud
Laurent
L
Université Bordeaux 1, Institut des Sciences Moléculaires, UMR-CNRS 5255, 351, cours de la libération, 33405 Talence, France.
Landais
Yannick
Y
Renaud
Philippe
P
Robert
Frédéric
F
Castet
Frédéric
F
Lucarini
Marco
M
Schenk
Kurt
K
D000498:Allyl Compounds / Q000737:chemistry*; D001386:Azides / Q000737:chemistry; D003198:Computer Simulation; D007212:Indolizines / Q000138:chemical synthesis / Q000737:chemistry; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D011789:Quantum Theory; D012821:Silanes / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism; D013696:Temperature; D054836:Indolizidines
D000498:Allyl Compounds; D001386:Azides; D007212:Indolizines; D012821:Silanes; C037806:castanospermine; D054836:Indolizidines