Boron-Selective Biaryl Coupling Approach to Versatile Dibenzoxaborins and Application to Concise Synthesis of Defucogilvocarcin M
摘要:
An efficient synthetic method for versatile dibenzoxaborins based on boron-selective Suzuki-Miyaura cross-coupling between o-borylphenols and aryl halides or triflates bearing a 1,8-diaminonaphthalene-protected o-boryl group is reported. A short synthesis of defucogilvocarcin M was achieved using the proposed method in combination with several other boron-mediated transformations.
Acylalkylation of Arynes Generated from <i>o</i>-Iodoaryl Triflates with Hydrosilanes and Cesium Fluoride
作者:Mai Minoshima、Keisuke Uchida、Yu Nakamura、Takamitsu Hosoya、Suguru Yoshida
DOI:10.1021/acs.orglett.1c00279
日期:2021.3.5
An efficient method to generate aryne intermediates from o-iodoaryl triflates triggered by triethylsilane and cesiumfluoride is disclosed. This method realized the acylalkylation of arynes using easily available o-iodoaryl triflate-type precursors, which was difficult when using conventional nucleophilic activators. A wide range of (hetero)arenes including various fused benzothiazoles were successfully
A fair exchange: In the title reaction, alkynyllithium serves as an initiator for benzyne generation through an iodine–lithium exchange (see scheme; Tf=trifluoromethanesulfonyl). When performed in the presence of stoichiometric amounts of a nucleophile, the generated benzyne undergoes attack by lithio nucleophiles to generate aryllithium, which is then iodinated by iodoalkyne to give the iodoarenes
Total synthesis of the unnatural enantiomer of deacetylravidomycin M was accomplished. The key steps include, (1) aryl C-glycosidation of the azido-bearing fucosyl acetate 2 by using catalytic Sc(OTf)3, (2) the [2+2] cycloaddition reaction of alkoxybenzyne bearing an azido sugar to ketene silyl acetal, and (3) the ring expansion reaction of alkoxybenzocyclobutenone. The synthesis revealed that the
Preparation of 2-Substituted 3-Methoxycarbonyl-4-methoxyfurans that Allow Access to Highly Functionalized Naphthalenes via Regioselective Cycloaddition with Alkoxybenzyne
A facile synthetic method of 2-substituted 3-methoxycarbonyl-4-methoxyfurans has been developed, allowing construction of highly functionalized naphthalene derivatives via (1) regioselective benzyne [4+2] cycloaddition with α-alkoxybenzyne and (2) reductive aromatization.
The first observation of the stereospecificity in the benzyne-olefin [2 + 2] cycloaddition is described. The key points reside in (1) the efficient method for generating benzyne species by the halogen-lithium exchange reaction of ortho-halo aryl triflates, and (2) the choice of ketene silyl acetal as the partner olefin.