Synthesis and Chemistry of Donor/Acceptor-Substituted Cyclopropenes
摘要:
Rhodium(II) acetate, or trifluoroacetate-catalyzed decomposition of 1-diazo-2-(trialkylsiloxy)propenes with electron-withdrawing groups at the 1-position results in the formation of highly reactive cyclopropenes. These cyclopropenes contain both donor and acceptor substituents on the alkene and are very susceptible to ring opening and fragmentation reactions, Nevertheless, when appropriately functionalized with bulky substituents they can be of sufficient stability to be isolated and characterized.
Palladium-catalyzed anti-Markovnikov oxidative acetalization of activated olefins with iron(<scp>iii</scp>) sulphate as the reoxidant
作者:Rodney A. Fernandes、Sandhya S. Yadav、Praveen Kumar
DOI:10.1039/d1ob02227j
日期:——
efficient palladium-catalyzed anti-Markovnikov oxidative acetalization of activated terminal olefins with iron(III) sulfate as the reoxidant. This methodology requires mild reaction conditions and shows high regioselectivity toward anti-Markovnikov products and compatibility with a wide range of functional groups. Iron(III) sulphate was the sole reoxidant used in this method. Various olefins like vinylarenes
本文公开了以硫酸铁( III )为再氧化剂的活性末端烯烃的高效钯催化抗马尔科夫尼科夫氧化缩醛化反应。该方法需要温和的反应条件,并显示出对抗马尔科夫尼科夫产物的高区域选择性以及与多种官能团的相容性。硫酸铁( III ) 是该方法中使用的唯一再氧化剂。各种烯烃,如乙烯基芳烃、芳基烯丙基醚、丙烯酸芳基或苄基丙烯酸酯和高烯丙醇都反应良好,提供抗马尔科夫尼科夫缩醛,其中一些代表正交官能化的 1,3-和 1,4-二氧化化合物。
Synthesis of Bridged Benzazocines and Benzoxocines by a Titanium-Catalyzed Double-Reductive Umpolung Strategy
作者:Plamen Bichovski、Thomas M. Haas、Daniel Kratzert、Jan Streuff
DOI:10.1002/chem.201405852
日期:2015.2.2
A sequence of two titanium(III)‐catalyzed reductive umpolung reactions is reported that allows the rapid construction of benzazo‐ and benzoxozine building blocks. The first step is a reductive cross‐coupling of quinolones or chromones with Michael acceptors. This reaction proceeds with complete syn‐selectivity for the quinolone functionalization while the anti‐diastereomers are obtained as the major
Direct conjugate alkylation of α,β-unsaturated carbonyls by Ti<sup>III</sup>-catalysed reductive umpolung of simple activated alkenes
作者:Plamen Bichovski、Thomas M. Haas、Manfred Keller、Jan Streuff
DOI:10.1039/c5ob02631h
日期:——
The titanium(III)-catalysed cross-selective reductive umpolung of Michael-acceptors represents a unique direct conjugate β-alkylation reaction. It allows the cross-selective preparation of 1,6- and 1,4-difunctionalised building blocks without the requirement of stoichiometric organometallic reagents. In this full paper, the development and scope of the titanium(III)-catalysed cross-selective reductive
A system for in situ regeneration of SmI2 from SmI3 is described which allows the annulation of ketones to γ-lactones, the deoxygenation of oxiranes to olefins and radical π-cyclization to be conducted with 10 mole % SmI2.
A Bifunctional β-Isocupreidine Derivative as Catalyst for the Enantioselective Morita-Baylis-Hillman Reaction and a Mechanistic Rationale for Enantioselectivity
作者:Gianluca Martelli、Mario Orena、Samuele Rinaldi
DOI:10.1002/ejoc.201200405
日期:2012.8
Starting fromβ-isocupreidine (β-ICD), a series of difunctional catalysts were synthesized to ascertain their usefulness in the asymmetric Morita–Baylis–Hillman (MBH) reaction. The trichloroacetylcarbamate derivative was found to give the (R)-MBH adducts in excellent optical purities (90–99 % ee) and moderate to good yields (43–83 %), in some cases, better than β-ICD. A number of acrylates were also