Diastereoselective synthesis of cis-1,2-disubstituted cyclopropanols and cyclopent-3-enols via SmI2 mediated C–N(Bt) bond cleavage
摘要:
Diastereoselective synthesis of cis-1,2-disubstituted cyclopropanols and cyclopent-3-enols has been achieved from readily available beta-benzotriazolyl ketones (beta-Bt ketones) via a C-N(Bt) bond cleavage/cyclization process promoted by SmI2/HMPA. (C) 2015 Elsevier Ltd. All rights reserved.
cetyltrimethylammonium bromide in catalyzing C–N bond formation has been studied with respect to N-alkylations of benzotriazole (Bt). Alkylations with various alkylating agents and the addition of Bt across activateddoublebonds in the Michael fashion occurred successfully in fair-to-good yields in the aqueous micellar regime. These reactions provided a mixture of N-1 and N-2 alkylated products, with a marked preference
Résumé The catalyst-free reactions of activated alkenes with primary and secondary amines were investigated leading to various mono- and di-hydroamination products, the latter being rare and original. These reactions were shown to depend first on the strength of the nucleophile. Temperature and steric hindrance of the reagents were the other key factors controlling the selectivity of these aza-Michael reactions. In spite of their poor nucleophilicities, some N-heterocyclic amines could react with different activated alkenes affording valuable intermediates. Such results tended to demonstrate the hydrogen-bonding interactions between activated alkenes and poly-nitrogen aromatic cycles may control these concerted or fully conjugate aza-Michael additions. Supplementary Materials: Supplementary material for this article is supplied as a separate file: mmc1.doc
Enantioselective conjugate addition of benzotriazole to α,β-enones catalyzed by prolinol derivatives with moderate yields and enantioselectivities was reported. Studies of stereoelectronic effects of the catalyst showed that the transition state could be of a hydrogen bonding activation mode, and fine tuning of the substituents on the aryl moiety of the catalyst is important for the reaction stereoselectivities.
A convenient approach to β-heteroarylated (C–N bond) ketones from Cs2CO3 promoted reaction between propargyl alcohols and nitrogen-heterocycles
作者:M. Bhanuchandra、Malleswara Rao Kuram、Akhila K. Sahoo
DOI:10.1039/c2ob25165e
日期:——
effectively undergo redox-isomerization conjugate addition (RICA) with NH-heteroarenes. Reaction of 3-substituted pyrazoles or indazole with propargyl alcohols enables highly regioselective products. A diverse range of NH-bearing nucleophiles such as: pyrazoles, imidazole, triazoles, pyrrole, indoles and aniline participate in this reaction and deliver the corresponding β-heteroarylated ketones.