Cross-metathesis of allyl halides with olefins bearing an α-alkoxy amide group
摘要:
We have examined whether the allyl halide cross-metathesis reaction tolerates alpha-alkoxy amide groups. Ruthenium-based catalysts I-Ill did not catalyze the cross-metathesis of allyl halides in the presence of an alpha-alkoxy N,N-dimethylamide group to any appreciable extent, but the reaction could tolerate either a bulky N,N-diisopropylamide or Weinreb amide group. In particular, the Grubbs-Hoveyda-Blechert 2nd generation catalyst (III) efficiently catalyzed the cross-metathesis of allyl halides with olefins bearing a Weinreb amide group. (C) 2011 Elsevier Ltd. All rights reserved.
Efficient Medium Ring Size Bromolactonization Using a Sulfur-Based Zwitterionic Organocatalyst
作者:Yi An Cheng、Tao Chen、Chong Kiat Tan、Jun Jie Heng、Ying-Yeung Yeung
DOI:10.1021/ja307210n
日期:2012.10.10
Catalytic bromolactonization of long-chain olefinic acids resulting in the efficient synthesis of medium-sized lactones is reported using a zwitterionic catalyst and stoichiometric N-bromosuccinimide halogen source. The reaction was found to be more efficient at 0 degrees C than at room temperature, which could be attributed to the temperature dependence of the zwitterionic catalyst.