Palladium-Catalyzed[4+2]and[6+2]Dipolar Cycloadditions for the Construction of Benzo[d]isothiazole 1,1-Dioxide Fused 1,3-Oxazinanes and 1,3-Oxazocanes

Comprehensive Summary,The Pd-catalyzed dipolar cycloaddition represents a significant synthetic strategy for the construction of useful heterocyclic compounds.This study developed the dipolar[4+2]and[6+2]cycloaddition reactions of benzo[d]isothiazole 1,1-dioxides(BDs)leading to the synthesis of BD-fused 1,3-oxazinane and 1,3-oxazocane derivatives,respectively.In particular,the synthesis of BD-fused 1,3-oxazinanes demonstrated regio-and enantioselective characteristics,resulting in products with good yields,enantioselectivity and regioselectivity(if applicable).Furthermore,the[6+2]cycloaddition reaction developed in this work represented the first strategy for the synthesis of medium-sized ring compounds based on BDs.

Palladium-catalyzed annulative allylic alkylation for regioselective construction of indole-fused medium-sized cyclic etherS

A new palladium-catalyzed annulative allylic alkylation(AAA)reaction of 2-(indol-2-yl)phenols with dual allylic electrophiles such as isobutylene dicarbonate and butene dicarbonate is described,leading to the regioselective synthesis of tetracyclic medium-sized cyclic ethers possessing a bridged aryl-indole scaf-fold,namely,benzo[2,3]oxocino[4,5-b]indoles and benzo[2,3]oxepino[4,5-b]indoles,in good to excellent yields.This protocol demonstrates a broad substrate scope,good compatibility with substituents and high regioselectivity,providing a catalytic and flexible method for creating bridged aryl-indole skeletons.

Copper catalyzed borylative cyclization of 3-arylallyl carbamoyl chloride with B_(2)pin_(2):stereoselective synthesis of cis-2-aryl-3-boryl-γ-lactams

Borylative cyclization of E-3-arylallyl carbamoyl chlorides is achieved through copper catalyzed intramolecular carboboration with B_(2)pin_(2).2-Aryl-3-boryl-γ-lactams are formed with exclusive cisdiastereoselectivity.CuBr-Dppp combination gives the best outcomes.The substrate scope is profiled.

Allylation and alkylation of oxindoleketimines via imine umpolung strategy

When treated with an alkoxide base like t-BuOK in aprotic solvent,N-di phenyl methyl imino oxindoles,made conveniently through condensation of corresponding isatins with N-di phenyl methyl amine,are deprotonated to form azaallyl anions.Allylation and alkylation of this type of intermediates proceed smoothly with diverse C-electrophiles.Acidic work up finishes 3-amino-3-allyl/alkyl oxindoles.The overall transformation equals to an umpolung process at the C3 of isatins.

NFSI-catalyzed S–S bond exchange reaction for the synthesis of unsymmetrical disulfides

The metal-free S–S bond exchange reaction of symmetrical disulfides catalyzed by NFSI is described. This novel protocol provides a facile and efficient approach to accessing important unsymmetrical disulfides.Furthermore, this strategy could also be utilized in the late-stage functionalization of amino acids, drugs,and natural products. The broad substrate scope, good functional group tolerance and easy accessibility of catalyst indicate that this strategy affords a green and practical complementary method to various unsymmetrical disulfides.

Metal-free direct C(sp^(3))-H functionalization of 2-alkylthiobenzoic acid to access 1,3-benzooxathiin-4-one

Metal-free direct α-C(sp^(3))-H intramolecular cyclization of 2-alkylthiobenzoic acid in the presence of Selectfluor is described.This novel strategy provides a facile and efficient method to access important 1,3-benzooxathiin-4-one derivatives with good functional groups tolerance and yields.

Rhodium-catalyzed dearomative rearrangement of 2-oxypyridines with cyclopropenes: access to N-alkylated 2-pyridones

A rhodium-catalyzed dearomative rearrangement reaction of 2-oxypyridines has been developed by using cyclopropenes as carbene precursors.This protocol features broad substrate scope and mild reac-tion conditions,providing a reliable and practical approach for the highly efficient synthesis of 2-alkylated 2-pyridone derivatives from readily available O-substituted pyridine compounds.

Recent advances in directα-C(sp^(3))-H bond functionalization of thioethers

Thioether skeletons are widely present in drugs,natural products,functional materials,and life science.In the past decade,the selective C–H functionalization of thioethers has been extensively studied to construct novel thioether derivatives.This mini-review systematically introduces the recent advances in the field of the directα-C(sp^(3))-H functionalization of thioethers.

Pd-Catalyzed Highly Regioselective Hydroesterification of Terminal Alkyl Olefins with Formates

Comprehensive Summary A Pd-catalyzed regioselective hydroesterification of alkyl terminal olefins with aryl formates is described.A wide variety of linear carboxylic esters bearing various functional groups can be obtained in good yields with high regioselectivities under mild reaction conditions by using 1,2-DTBPMB or(p-F-Ph)3P as ligand.The reaction process is operationally simple and requires no handling of toxic CO or strong acid.The resulting aryl esters can be readily converted to other carboxylic acid derivatives.