Intramolecular addition of carbon radicals to aldehydes: synthesis of enantiopure tetrahydrofuran-3-ols
摘要:
A simple and efficient substrate-controlled asymmetric synthesis of enantiopure tetrahydrofuran-3-ols by a 5-exo-trig radical cyclization is described. This cyclization occurs when a delta-carbon radical adds intramolecularly to the carbonyl group of an aldehyde. The delta-carbon radicals can be efficiently produced from the tin hydride mediated deselenenylation of 5-phenylseleno-3-oxapentanals, which were easily prepared starting from commercially available enantiopure epoxides or chlorohydrins. (c) 2007 Elsevier Ltd. All rights reserved.
Intramolecular addition of carbon radicals to aldehydes: synthesis of enantiopure tetrahydrofuran-3-ols
摘要:
A simple and efficient substrate-controlled asymmetric synthesis of enantiopure tetrahydrofuran-3-ols by a 5-exo-trig radical cyclization is described. This cyclization occurs when a delta-carbon radical adds intramolecularly to the carbonyl group of an aldehyde. The delta-carbon radicals can be efficiently produced from the tin hydride mediated deselenenylation of 5-phenylseleno-3-oxapentanals, which were easily prepared starting from commercially available enantiopure epoxides or chlorohydrins. (c) 2007 Elsevier Ltd. All rights reserved.
Ring-Closure Reactions through Intramolecular Displacement of the Phenylselenonyl Group by Nitrogen Nucleophiles: A New Stereospecific Synthesis ofN-Tosyl andN-Benzoyl-1,3-oxazolidin-2-ones fromβ-Hydroxyalkyl Phenyl Selenides
3-oxazolidin-2-ones from the easily available beta-hydroxyalkyl phenyl selenides is presented. After transformation into the N-tosyl or N-benzoyl carbamates, the selenides were oxidized to the corresponding selenones. The key step of the process is the ring-closure reaction, which occurs by stereospecific intramolecular nucleophilic substitution of the selenonegroup by the nitrogen atom of the carbamate. Enantiomerically
A simple and efficient substrate-controlled asymmetric synthesis of enantiopure tetrahydrofuran-3-ols by a 5-exo-trig radical cyclization is described. This cyclization occurs when a delta-carbon radical adds intramolecularly to the carbonyl group of an aldehyde. The delta-carbon radicals can be efficiently produced from the tin hydride mediated deselenenylation of 5-phenylseleno-3-oxapentanals, which were easily prepared starting from commercially available enantiopure epoxides or chlorohydrins. (c) 2007 Elsevier Ltd. All rights reserved.