Catalytic Enantio- and Diastereoselective Alkylations with Cyclic Sulfamidates
作者:Thomas A. Moss、Beatriz Alonso、David R. Fenwick、Darren J. Dixon
DOI:10.1002/anie.200905329
日期:2010.1.12
Open for business: The enantio‐ and diastereoselective nucleophilic ring opening of five‐membered and six‐membered cyclicsulfamidates under asymmetric phase‐transfer catalysis is presented. A range of pro‐nucleophiles have been successfully alkylated in good yields and in good to excellent enantioselectivites.
A new enantioselective α‐benzylation and α‐allylation of α‐tert‐butoxycarbonyllactones was devloped. α‐Benzylation and α‐allylation of α‐tert‐butoxycarbonylbutyrolactone and α‐tert‐butoxycarbonylvalerolactone under phase‐transfer catalytic conditions (50% cesium hydroxide, toluene, −60 °C) in the presence of (S,S)‐3,4,5‐trifluorophenyl‐NAS bromide (1 mol%) afforded the corresponding α‐substituted
An efficient catalytic enantioselective fluorination of tert-butoxycarbonyl lactones and lactams is reported. Reactions of the lactone substrates proceeded smoothly in an alcoholic solvent with a catalytic amount of chiral Pd(II) complex. In the case of the less acidic lactam substrates, concurrent use of the Pd complex and 2,6-lutidine as a cocatalyst was effective. Under the reaction conditions, the fluorinated lactones and lactams were obtained in good yield with excellent enantioselectivity (94-99% ee).