Construction of Tetrahydrofuran-3-ones from Readily Available Organochalcogen Precursors via Radical Carbonylation/Reductive Cyclization
摘要:
[GRAPHICS]b-Hydroxyalkyl aryl chalcogenides, readily available by regioselective ring-opening of epoxides with nucleophilic benzeneselenolate or tellurolate, were O-alkylated by treatment with ethyl propiolate or (E)-1,2-bis(phenylsulfonyl)ethylene. Subsequent carbonylation/reductive cyclization in the presence of AIBN/TTMSS and carbon monoxide (80 atm) afforded tetrahydrofuran-3-ones in moderate to good yields.
Regioselective ring-opening reactions of 1,2-epoxides with thiols and arylselenols directly promoted by [Bmim]BF4
作者:Ming-Hua Yang、Guo-Bing Yan、Yun-Fa Zheng
DOI:10.1016/j.tetlet.2008.08.109
日期:2008.11
Regioselective ring-openingreactions of 1,2-epoxides with ArSH and ArSeH promoted by ionic liquid [Bmim]BF4 were investigated. A variety of β-hydroxy selenides and β-hydroxy sulfides were obtained in excellent yields (81–99%) with good regioselectivities using a mild, simple and environmentally benign procedure.
Under acidic conditions zinc reduces diselenides to afford selenols, which can be either isolated or treated in situ with alkyl halides to produce alkyl selenides or with epoxides to give β-hydroxyselenides.
An efficient and simple one-pot procedure for the synthesis of β-hydroxy selenides in aqueous media through highly regioselective ring-opening of epoxides with diphenyl diselenide in the presence of active metallic indium is described.
Treatment of diphenyl diselenide with tributylphosphine in an alkaline medium forms phenylselenolate ion which converts alkyl halides, α,β-unsaturated ketones, and epoxides into alkyl selenides, (phenylseleno)alkenones, and β-(phenylseleno) alkanols, respectively, in high yield. Selenation of 3α-bromocholestane gives 3β-(phenylseleno)cholestane with complete inversion of the configuration.
In this communication we report the synthesis and the characterization of the first solid and air-stable selenolates, starting from commercially available phenylselenenyl halides and elemental zinc. These reagents were efficiently employed in the ring opening of epoxides as well as in other nucleophilic substitution and addition reactions showing an unexpected rate acceleration in water suspension