Thermally Induced Carbohydroxylation of Styrenes with Aryldiazonium Salts
作者:Stephanie Kindt、Karina Wicht、Markus R. Heinrich
DOI:10.1002/anie.201601656
日期:2016.7.18
The radical carbohydroxylation of styrenes with aryldiazonium salts has been achieved under mild thermal conditions. A broad range of aryldiazonium salts was tolerated, and the reaction principle based on a radical-polar crossover mechanism could be extended to carboetherification as well as to a two-step, metal-free variant of the Meerwein arylation leading to stilbenes.
Palladium/Acid Relay Catalyzed Tandem Heck Coupling/6‐Endo Cyclization between ortho‐Halogenated Benzoates and Unactivated Terminal Alkenes for the Synthesis of 1‐Isochromanones
We report a unique and expeditiousroute to synthesize 1‐isochromanone derivatives through palladium catalyzed tandem Heck coupling/6‐endo hydroacyloxylation cyclization between readily available ortho‐halogenated benzoates and unactivated alkenes. Various 2‐bromo or 2‐iodo benzoates can be coupled efficiently with a broad range of alkenes to afford functionalized 1‐isochromanones in high yields. Significantly
o-Cyanobenzyllithium (3) was efficiently generated by lithium-tellurium exchange of the corresponding benzylic telluride 2 prepared in situ from lithium butanetellurolate and α-bromo-o-tolunitrile (1). Reaction of ketones or aldehydes with 3 afford substituted 2-hydroxyethylbenzonitriles 4 in high yields. The subsequent acid-catalyzed lactonization gave 3-substituted 3,4-dihydroisocoumarins 5 in good yields. All these successive reactions could be performed in the same reaction flask without isolation of intermediates.
A visible-light RuII photoredox Meerwein synthesis of isochromanones and isochromenones is described starting from diazonium salts of differently substituted anthranilic acids and various alkenes. This approach has allowed the reliable and efficient preparation of structures found in many biologically active molecules or used in materials chemistry.