undergoes facile thermal cyclisation affording nitrones 1c and 1d in good yield. Oximes E-5a,b with a terminal methyl substituent on the alkene moiety furnish nitrone only under the influence of an external electrophile [PhSeBr/AgBF4]. A terminal Ph substituent on 5c,d prohibits formation of the cyclic dipole irrespective of reaction conditions, and whilst 5d reacts to afford a bicyclic isoxazolofuranone
Deoxygenative α-alkylation and α-arylation of 1,2-dicarbonyls
作者:Shengfei Jin、Hang T. Dang、Graham C. Haug、Viet D. Nguyen、Hadi D. Arman、Oleg V. Larionov
DOI:10.1039/d0sc03118f
日期:——
challenging but synthetically indispensable approach to α-branched carbonyl motifs that are widely represented among drugs, natural products, and synthetic intermediates. Here, we describe a simple approach to generation of boron enolates in the absence of strong bases that allows for introduction of both α-alkyl and α-aryl groups in a reaction of readily accessible 1,2-dicarbonyls and organoboranes. Obviation
Exploration of click reaction for the synthesis of modified nucleosides as chitin synthase inhibitors
作者:Preeti M. Chaudhary、Sayalee R. Chavan、Fazal Shirazi、Meenakshi Razdan、Prachi Nimkar、Shailaja P. Maybhate、Anjali P. Likhite、Rajesh Gonnade、Braja G. Hazara、Mukund V. Deshpande、Sunita R. Deshpande
DOI:10.1016/j.bmc.2009.02.019
日期:2009.3
Click reaction approach toward the synthesis of two sets of novel 1,2,3-triazolyl linked uridinederivatives 19a–19g and 21a–21g was achieved by Cu(I)-catalyzed 1,3-dipolar cycloaddition of 5′-azido-5′-deoxy-2′,3′-O-(1-methylethylidene)uridine (17) with propargylated ether of phenols 18a–18g and propargylated esters 20a–20g. Structure of one of the representative compound 19d was unambiguously confirmed
The versatility of the reaction was established by synthesizing a range of α-keto esters by treatment of 2,2-dibromoethanones, derivedfrom aryl or hetaryl ketones, with dimethyl sulfoxide and a cyclic or acyclic primary or secondary alcohol. The mechanism of the reaction was established by means of a detailed study. ketones- esters - oxidations - esterifications -alcohols
Divergent Photocatalytic Reactions of α-Ketoesters under Triplet Sensitization and Photoredox Conditions
作者:Jian Zheng、Xiao Dong、Tehshik P. Yoon
DOI:10.1021/acs.orglett.0c02314
日期:2020.8.21
The long-lived triplet excited states of transition metal photocatalysts can activate organic substrates via either energy- or electron-transfer pathways, and the rates of these processes can be influenced by rational tuning of the reaction conditions. The characteristic reactive intermediates generated, however, are distinct and can exhibit very different reactivity patterns. This mechanistic diversity