Development of N,N-bis(perfluoroalkanesulfonyl)squaramides as new strong Brønsted acids and their application to organic reactions
作者:Cheol Hong Cheon、Hisashi Yamamoto
DOI:10.1016/j.tet.2010.03.120
日期:2010.6
l groups have been developed and applied to several organic reactions. These squaramides are bench-stable and exhibit much higher reactivities in several organic reactions than squaric acid itself. N,N-Bis(trifluoromethanesulfonyl)squaramide 2a was applied to the Mukaiyama aldol reaction and Mukaiyama Michael reaction. Mechanistic studies revealed that the Brønsted acid might be the predominant catalyst
new approach has been demonstrated for the regiospecific aldol synthesis by the simultaneous addition of α-halo carbonyl derivatives and aldehydes or ketones to a suspension of diethylaluminum chloride and zinc in tetrahydrofuran at low temperature. This technique is also employable under mild conditions for the Reformatsky reaction to give β-hiydroxy esters in excellent yield. One of the unique synthetic
Catalytic asymmetric aldol reactions. Use of a chiral (acyloxy)borane complex as a versatile Lewis-acid catalyst
作者:Kyoji Furuta、Tohru Maruyama、Hisashi Yamamoto
DOI:10.1021/ja00003a047
日期:1991.1
In the presence of 20 mol% of a chiral (acyloxy)borane (CAB) complex prepared from (2R,3R)-2-O(2,6-diisopropoxybenzoyl)tartaric acid and borane-tetrahydrofuran, various allyltrimethylsilanes react with achiral aldehydes to afford the corresponding homoallylic alcohols in good yields with high diastereo- and enantioselectivities. Furthermore, the reactivity of allylation can be improved without reducing
Aldol Reactions of α-Bromoalkyl Phenyl Ketones and Aldehydes with Tin(IV) Iodide and Tetrabutylammonium Iodide
作者:Yoshiro Masuyama、Masaru Ohtsuka、Ayako Kondo
DOI:10.1055/s-2006-951550
日期:——
Aldol reactions of α-bromoacetophenone and aldehydes in dichloromethane produced the corresponding E-α,β-unsaturated ketones at 25 °C with one equimolar amount of tin(IV) iodide, one equimolar amount of tetrabutylammonium iodide and one equimolar amount of N,N-diisopropylethylamine, and produced the corresponding β-hydroxy ketones at -80 °C with one equimolar amount of tin(IV) iodide and two equimolar
α-溴苯乙酮和醛在二氯甲烷中的羟醛反应在 25 °C 下产生相应的 E-α,β-不饱和酮,其中包含一等摩尔量的碘化锡 (IV)、一等摩尔量的四丁基碘化铵和一等摩尔量的 N,N -二异丙基乙胺,并在 -80 °C 下用一等摩尔量的碘化锡 (IV) 和两等摩尔量的四丁基碘化铵生成相应的 β-羟基酮。在 -80 °C 的二氯甲烷中,使用一等摩尔量的碘化锡 (IV) 和两等摩尔量的四丁基碘化铵,α-溴苯丙酮与醛反应,选择性地提供相应的顺-α-甲基-β-羟基酮。
Reformatsky type reaction by means of Bu3SnA1et2 or Bu3Pba1et2
Treatment of α-halo carbonyl compounds with title Sn-Al or Pb-Al reagents provides enolates which react with aldehydes or ketones to give β-hydroxy carbonyl compounds effectively.