Regio- and enantioselective bioreduction of methyleneketoesters using both polymeric resin and cellulose matrix
摘要:
Methyleneketoesters were prepared in >90% yield by performing an IBX oxidation of Morita-Baylis-Hillman adducts. A methodology was developed to achieve methyl 3-aryl-3-keto-2-methylenepropanoate reduction using a screening of yeast strains in three different reaction procedures to obtain products with both high yield and diastereoselectivity. The reactions conducted in water provided inferior yields (50%) for substrates 2b-c. Employing Amberlite (R) XAD7HP which was a substrate reservoir that also immediately extracted the products from the reaction medium after their formation, syn-4a-c and anti-4a-c were isolated in 60-70% yield, with high stereoselectivity (98-99% ee). The best results were obtained using substrates adsorbed on filter paper which provided products yields above 70%, a 99% ee and a diastereomoeric ratio (syn-4: anti-4) 9:1. Cellulose matrix has excellent potential to be successfully employed in general biocatalytic reactions. (C) 2013 Elsevier B.V. All rights reserved.
Hypervalent iodine catalysis for selective oxidation of Baylis–Hillman adducts via in situ generation of o-iodoxybenzoic acid (IBX) from 2-iodosobenzoic acid (IBA) in the presence of oxone
作者:Raktani Bikshapathi、Parvathaneni Sai Prathima、Vaidya Jayathirtha Rao
DOI:10.1039/c6nj02628a
日期:——
An efficient, environmentally benign, eco-friendly protocol for selectiveoxidation of primary and secondary Baylis–Hillman alcohols to the corresponding carbonyl compounds has been developed. We have demonstrated the catalytic use of o-iodoxybenzoic acid (IBX) generated in situ from 2-iodosobenzoic acid (IBA) in the presence of oxone (2KHSO5·KHSO4·K2SO4) as a co-oxidant. This efficientmethod notably
已经开发出一种有效的,对环境无害的,环境友好的方案,用于将伯利兹和仲伯利兹-希尔曼醇选择性氧化为相应的羰基化合物。我们已经证明了在氧酮(2KHSO 5 ·KHSO 4 ·K 2 SO 4)作为助氧化剂存在下,由2-碘代苯甲酸(IBA)原位生成的邻碘氧苯甲酸(IBX)的催化用途。这种有效的方法尤其可以在不使用任何有毒重金属和直接使用棘手的IBX的情况下更好地提高产量。此外,可以通过还原后处理方便地回收合成的催化剂。
[3 + 2] Annulations between indoles and α,β-unsaturated ketones: access to pyrrolo[1,2-a]indoles and model reactions toward the originally assigned structure of yuremamine
作者:Haokun Li、Zhonglei Wang、Liansuo Zu
DOI:10.1039/c5ra11904a
日期:——
A direct [3 + 2] annulation reaction between indoles and α,β-unsaturatedketones is reported, which allows for the efficient assembly of densely substituted, highly functionalized pyrrolo[1,2-a]indoles. Model reactions toward the originally assigned structure of yuremamine are also described, leading to the successful construction of the core with required functionality.
据报道吲哚和α,β-不饱和酮之间有直接的[3 + 2]环化反应,可以有效地组装密集取代的高度官能化的吡咯并[1,2- a ]吲哚。还描述了针对最初分配的紫杉胺结构的模型反应,从而成功构建了具有所需功能的核。
Stereoselective Radical Cyclization Cascades Triggered by Addition of Diverse Radicals to Alkynes To Construct 6(5)–6–5 Fused Rings
作者:Lin Huang、Liu Ye、Xiao-Hua Li、Zhong-Liang Li、Jin-Shun Lin、Xin-Yuan Liu
DOI:10.1021/acs.orglett.6b02599
日期:2016.10.21
Cascade radical cyclization of alkynyl ketones with various carbon- and heteroatom-centered radical precursors via a sequential radical addition/1,5-H radical shift/5-exo-trig/radical cyclization process was realized for the first time. This method provides a strategically novel and step-economical protocol for diversity-oriented synthesis of a wide range of carbocyclic and heterocyclic 6(5)–6–5 fused
Diamine-mediated degradative dimerisation of Morita–Baylis–Hillman ketones
作者:Ajit Kumar Jha、Anju Kumari、Srinivasan Easwar
DOI:10.1039/c9cc10068g
日期:——
A degradative dimerisation of Morita-Baylis-Hillmanketones was observed in the presence of a primary diamine. The reaction proceeded swiftly to produce methylene-bridged 1,3-dicarbonyl compounds. A brief mechanisticinvestigation alluded to a retro-Mannich reaction as the key step of the transformation.
Unsymmetrical N,N'-functionalization of hydrazine by insertion into Morita–Baylis–Hillman ketones
作者:Ajit Kumar Jha、Sarita、Srinivasan Easwar
DOI:10.1016/j.tetlet.2021.152971
日期:2021.4
A simultaneous unsymmetrical N,N'-functionalization of hydrazine was realized by a base-mediated insertion into Morita–Baylis–Hillman (MBH) ketones. The atom-economic transformation involves the formation of two carbon–nitrogen bonds accompanied by the cleavage of a carbon–carbon bond, and results in the formation of N-acyl-N'-alkyl substituted hydrazines in good yields over a range of MBH ketones