5,5′-Dimethyl-3,3′-azoisoxazole as a new heterogeneous azo reagent for esterification of phenols and selective esterification of benzylic alcohols under Mitsunobu conditions
3′-azoisoxazole is used as a new efficient heterogeneous azo reagent for the highly selective esterification of primary and secondary benzylic alcohols and phenols with aliphatic and aromatic carboxylic acids via Mitsunobu protocols. The reaction is highly selective for primary benzylic alcohols versus secondary ones, aliphatic alcohols and also phenols. The isoxazole hydrazine byproduct can be simply isolated
A novel photochemical Wittig reaction for the synthesis of 2-aryl/alkylbenzofurans
作者:Somnath Ghosh、Jhantu Das
DOI:10.1016/j.tetlet.2010.12.104
日期:2011.3
The synthesis of 2-aryl/alkylbenzofurans has been achieved in high yields under photochemical conditions from readily accessible and suitably substituted phosphonium bromides by an intramolecular photochemical Wittigreaction onto aryloxycarbonyl groups.
Unexpected migration of a benzoyl group in the intramolecular Wittig reaction of o-acyloxybenzylidenephosphoranes with benzoyl chlorides: One-pot synthesis of isomeric 3-benzoyl-2-phenylbenzofurans
The reaction of o-acyloxybenzylidenetriphenylphosphoranes with substituted benzoyl chlorides in an aprotic solvent led, together with the expected 2-phenylbenzofuran, to isomeric 3-benzoyl-2-phenylbenzofuran derivatives. This result formally corresponds to intramolecular migration of the benzoyl group from the ortho oxygen atom to the ylide carbanion via cyclization and ring opening of the starting
Regioselective synthesis of new EWG-Bearing 3-benzoyl-2-phenylbenzofurans by one-pot intramolecular acylation/thermal cyclization of phosphoranes and their CB1 antagonist activity
improved regioselective synthetic strategy, tandem ylide acylation and thermal cyclization of the acyl ylide intermediate. Using our optimized method, only one 3-acyl regioisomer was obtained and the yields were highly improved (up to 92 %) comparing to the previously reported method, expanding the scope of synthesis to a wide variety of new EWG-containing 3-benzoyl-2-phenylbenzofurans. The synthesized