BF3·OEt2-Mediated Highly Regioselective SN2-Type Ring-Opening of N-Activated Aziridines and N-Activated Azetidines by Tetraalkylammonium Halides
摘要:
A highly regioselective Lewis acid-mediated S(N)2-type ring-opening of N-sulfonylaziridines and azetidines with tetraalkylammonium halides in CH2Cl2 solution to afford 1,2- and 1,3-haloamines in excellent yields is described. An easy diastereoselective route toward substituted chiral N-tosylaziridines has been developed. The mechanism of ring-opening via S(N)2 pathway has been confirmed by the formation of chiral haloamines with excellent er and dr. Chloroamines obtained from 2,3-disubstituted aziridines were converted to the chiral N-tosylamines via radical dehalogenation.
Catalytic Asymmetric Cross-Aza-Benzoin Reactions of Aliphatic Aldehydes with<i>N</i>-Boc-Protected Imines
作者:Daniel A. DiRocco、Tomislav Rovis
DOI:10.1002/anie.201202442
日期:2012.6.11
Crossed: A catalyst system has been developed that allows the direct asymmetric coupling of aliphaticaldehydes and N‐Boc‐protected imines in a cross‐aza‐benzoin reaction (see scheme; Boc=tert‐butoxycarbonyl). The active catalyst is shown to react rapidly with the imine, however, the presence of an acid as co‐catalyst renders this process reversible and allows the regeneration of the catalyst.
BF<sub>3</sub>·OEt<sub>2</sub>-Mediated Highly Regioselective S<sub>N</sub>2-Type Ring-Opening of <i>N</i>-Activated Aziridines and <i>N</i>-Activated Azetidines by Tetraalkylammonium Halides
作者:Manas K. Ghorai、Amit Kumar、Deo Prakash Tiwari
DOI:10.1021/jo902244y
日期:2010.1.1
A highly regioselective Lewis acid-mediated S(N)2-type ring-opening of N-sulfonylaziridines and azetidines with tetraalkylammonium halides in CH2Cl2 solution to afford 1,2- and 1,3-haloamines in excellent yields is described. An easy diastereoselective route toward substituted chiral N-tosylaziridines has been developed. The mechanism of ring-opening via S(N)2 pathway has been confirmed by the formation of chiral haloamines with excellent er and dr. Chloroamines obtained from 2,3-disubstituted aziridines were converted to the chiral N-tosylamines via radical dehalogenation.