Hammam, Abou El-Fotooh G.; Fahmy; Amr, Abdel-Galil E., Indian Journal of Chemistry - Section B Organic and Medicinal Chemistry, 2003, vol. 42, # 8, p. 1985 - 1993
Chiral Squaramide-Catalyzed Michael/Alkylation Cascade Reaction for the Asymmetric Synthesis of Nitro-Spirocyclopropanes
作者:Bo-Liang Zhao、Da-Ming Du
DOI:10.1002/ejoc.201500533
日期:2015.8
diastereoselective and enantioselective cyclopropanation reaction has been developed by employing a Michael/alkylationcascadereaction between (E)-3-arylenechroman-4-one or (E)-2-arylideneindan-1-one derivatives and a bromonitroalkane with a chiral squaramide catalyst. This reaction constitutes a facile asymmetricsynthesis for nitro-spirocyclopropanes that have three adjacent stereogenic centers, including
A convenient palladium‐catalyzed carbonylation reaction for the efficient synthesis of (E)‐3‐benzylidenechroman‐4‐ones has been developed. Using TFBen as a solid CO source, a range of substituted (E)‐3‐benzylidenechroman‐4‐ones were prepared in moderate to good yields with 2‐iodophenols and allyl chlorides as the substrates. Additionally, substituted quinolin‐4(1H)‐ones can also be obtained with 2‐iodoaniline
Rh-catalyzed asymmetric transfer hydrogenation. This transformation allowed the reduction of both the C═C and C═O bonds and the formation of two stereocenters in high yields with excellent levels of diastereo- and enantioselectivities (up to >99:1 dr, up to >99% ee) in a single step through a dynamic kinetic resolution process using a low catalyst loading and HCO2H/DABCO as the hydrogen source.
通过Rh催化的不对称转移氢化反应,可以直接从(E)-3-亚苄基-苯并二氢吡喃酮中获得对映异构体富集的顺式-3-苄基-苯并二氢苯并二氢苯并二氢吡喃酚。这种转变可以降低C═C和C═O键,并以高收率形成两个立构中心,且非对映和对映选择性极好(高达> 99:1 dr,高达> 99%ee)。通过动态动力学拆分过程的一个步骤,即使用低催化剂负载量和HCO 2 H / DABCO作为氢源。
Facile synthesis of spiro chromanone-tetrahydrothiophenes with three contiguous stereocenters via sulfa-Michael/aldol cascade reactions
作者:Ya-Jian Hu、Xiao-Bing Wang、Su-Yi Li、Sai-Sai Xie、Kelvin D.G. Wang、Ling-Yi Kong
DOI:10.1016/j.tetlet.2014.11.026
日期:2015.1
A novel sulfa-Michael/aldol cascade reaction of (E)-3-arylidenechroman-4-ones with 1,4-dithiane-2,5-diol has been developed. This method provides a new practical and facile approach to 4′-hydroxy-2′-aryl-4′,5′-dihydro-2′H-spiro[chroman-3,3′-thiophen]-4-ones with three contiguous stereocenters in high yields. The transformation is atom-economic with good to excellent diastereoselectivities.
Asymmetric Hydrogenation of Racemic Allylic Alcohols via an Isomerization–Dynamic Kinetic Resolution Cascade
作者:Kun Wang、Saisai Niu、Xin Guo、Weijun Tang、Dong Xue、Jianliang Xiao、Huaming Sun、Chao Wang
DOI:10.1021/acs.joc.1c02916
日期:2022.3.4
Prochiral racemic allylic alcohols are converted to enantioenriched chiral alcohols bearing adjacent stereocenters catalyzed by a diamine diphosphine Ru complex in the presence of tBuOK. The protocol features a broad substrate scope (56 examples) and high diastereo- and enantioselectivities (up to >99:1 dr, >99% ee) and could be applied to the synthesis of enantioenriched chromane and indane compounds