Conversion of substituted benzyl ethers to diarylmethanes. A direct synthesis of diarylbenzofurans
摘要:
The Lewis acid catalyzed rearrangement of substituted benzyl ethers affords diarylmethanes in good yields. One of the products was converted into a diarylbenzofuran using a benzoylation/P4-tBu cyclization protocol. (C) 2012 Elsevier Ltd. All rights reserved.
oxa-[4+2] cycloaddition reaction promoted by a thioxanthylium photoredox catalyst under irradiation with green light has been developed. The reaction of ortho-quinone methides with styrenes smoothly affords the desired cycloadducts. Especially styrenes bearing electron-donating groups are efficiently transformed in this reaction. This method represents a sustainable way to carry out oxa-[4+2] cycloaddition
Quinine-catalyzed highly enantioselective cycloannulation of o-quinone methides with malononitrile
作者:Alafate Adili、Zhong-Lin Tao、Dian-Feng Chen、Zhi-Yong Han
DOI:10.1039/c4ob02602k
日期:——
2-Amino-3-cyano-4H-chromenes show great potential as novel anticancer agents. Here we report a quinine-catalyzed highly enantioselective formal 4 + 2 cycloaddition of ortho-quinone methides and malononitrile, providing a unique approach to 4-arylvinyl, 4-aryl and 4-vinyl 2-amino-3-cyano-4H-chromenes with excellent yields and enantioselectivities.
A one-pot oxidation/cycloaddition cascade synthesis of 2,4-diaryl chromans via ortho-quinone methides
作者:Yuk Fai Wong、Zhaobin Wang、Wen-Xu Hong、Jianwei Sun
DOI:10.1016/j.tet.2015.12.011
日期:2016.6
A one-pot oxidation/cycloaddition cascade for the synthesis of 2,4-diaryl chromans is developed. The reaction involves in situ oxidative generation of the unstable o-quinone methides followed by endo selective [4+2] cycloaddition with styrenes.
ortho-Quinone methides are useful transient synthetic intermediates in organic synthesis. These species are most often generated in situ by the acid- or base-mediated transformation of phenols that have been pre-functionalized at a benzylic position, or by biomimetic oxidation of the corresponding ortho-alkylphenols with metal oxidants or transition-metal complexes. Here we describe a method for the