Regioselective synthesis of chiral six- and seven-membered N-heterocycles from N-allyl carbohydrate nitrones: Tuning of regioselectivity by N-substitution
The intramolecularcycloaddition of N-allyl carbohydrate nitrones leads to enantiomerically pure six- and seven-membered nitrogen heterocycles and the regioselectivity of the cycloaddition was controlled by changing the substituent on the nitrogen atom of the N-allyl moiety.
A simple one-pot entry to cyclic ethers of varied ring sizes from diols via phosphonium ion induced iodination and base catalyzed Williamson etherification
作者:Biswajit Gopal Roy、Ashim Roy、Basudeb Achari、Sukhendu B. Mandal
DOI:10.1016/j.tetlet.2006.08.090
日期:2006.10
A novel and an efficient one-pot cyclization method using triphenylphosphine, iodine and a nitrogenous base has been established for the synthesis of cyclicethers of various ring sizes. This appears to follow a two-step procedure, which includes preferential substitution of one hydroxyl group by an iodide generated in situ followed by an intramolecular ringclosure through the attack of a free hydroxyl