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.
铑(I)催化剂促进邻炔基苯酚和苯胺转化为相应的苯并[ b ]呋喃和吲哚。假定该反应通过过渡的3-铑杂环中间体进行,该中间体可以用合适的亲电试剂捕获以得到多取代的杂环。在单取代的吸电子亲电体的情况下,与Heck-Mizoroki反应相比,可以获得优异的收率和选择性。在2-炔基吡啶亲电试剂的情况下,形成新的2-(苯并呋喃-3-基)乙烯基吡啶。
An Effective Method for the Synthesis of<sup>13</sup>C-Labeled Polyprenylhydroxybenzoic Acids
作者:Wolfgang Steglich、Martin Lang
DOI:10.1055/s-2005-861863
日期:——
The synthesis of side-chain 13C-labeled geranylgeranyl-4-hydroxybenzoic acids and geranylgeranyl-3,4-dihydroxybenzoic acids is described. The synthesis starts from O-protected methyl hydroxyiodobenzoates, which are transformed into Grignard reagents by low-temperature iodine-magnesium exchange according to Knochel’s procedure. Copper catalyzed cross-coupling with labeled geranylgeranyl bromide followed by deprotection affords the products with good yields and full retention of stereochemistry.
Rhodium(I) catalysts promote the transformation of o-alkynyl phenols and anilines to the corresponding benzo[b]furans and indoles. The reaction is postulated to proceed via a transient 3-rhodium heterocycle intermediate, which can be trapped with suitable electrophiles to give poly-substituted heterocycles. In the case of mono-substituted electron-withdrawn electrophiles, excellent yield and selectivity
铑(I)催化剂促进邻炔基苯酚和苯胺转化为相应的苯并[ b ]呋喃和吲哚。假定该反应通过过渡的3-铑杂环中间体进行,该中间体可以用合适的亲电试剂捕获以得到多取代的杂环。在单取代的吸电子亲电体的情况下,与Heck-Mizoroki反应相比,可以获得优异的收率和选择性。在2-炔基吡啶亲电试剂的情况下,形成新的2-(苯并呋喃-3-基)乙烯基吡啶。
Au–Ag Bimetallic Catalysis: 3‐Alkynyl Benzofurans from Phenols via Tandem C−H Alkynylation/Oxy‐Alkynylation
作者:Long Hu、Martin C. Dietl、Chunyu Han、Matthias Rudolph、Frank Rominger、A. Stephen K. Hashmi
DOI:10.1002/anie.202016595
日期:2021.5.3
The development of new methodologies enabling a facileaccess to valuable heterocyclic frameworks still is an important subject of research. In this context, we describe a dual catalytic cycle merging C−H alkynylation of phenols and oxy‐alkynylation of the newly introduced triple bond by using a unique redox property and the carbophilic π acidity of gold. Mechanistic studies support the participation
Enantiospecific Solvolytic Functionalization of Bromochlorides
作者:Alexander J. Burckle、Bálint Gál、Frederick J. Seidl、Vasil H. Vasilev、Noah Z. Burns
DOI:10.1021/jacs.7b07792
日期:2017.9.27
Herein, we report that under mild solvolytic conditions, enantioenriched bromochlorides can be ionized, stereospecifically cyclized to an array of complex bromocyclic scaffolds, or intermolecularly trapped by exogenous nucleophiles. Mechanistic investigations support an ionic mechanism wherein the bromochloride serves as an enantioenriched bromonium surrogate. Several natural product-relevant motifs
A new method for the arylative cyclization of o-alkynylphenols with aryldiazonium salts via dual photoredox/gold catalysis is described. The reaction proceeds smoothly at roomtemperature in the absence of base and/or additives and offers an efficient approach to benzofuran derivatives. The scope of the transformation is wide, and the limitations are discussed. The reaction is proposed to proceed through