Regiodivergent Halogenation of Vinylogous Esters: One-Pot, Transition-Metal-Free Access to Differentiated Haloresorcinols
作者:Xiaohong Chen、Jenny S. Martinez、Justin T. Mohr
DOI:10.1021/ol503561x
日期:2015.1.16
vinylogous esters and sulfonyl halide halogen donors. Either the 4- or 6-haloresorcinol isomer is accessible from a common precursor. In contrast to conventional oxidants for arene halogenation, mild sulfonyl halides allow broad functional group compatibility. The strategy inherently differentiates the two resorcinol oxygen atoms and enhances the potential for complexmolecule synthesis.
Here we describe the realization of a one-pot protocol for the β-C–H halogenation of cyclic enones via umpolung of the β-carbon. The developed method includes hydrazone formation and selective β-halogenation (bromination, chlorination) with N-bromosuccinimide and Palau’chlor (2-chloro-1,3-bis(methoxycarbonyl)guanidine) followed by hydrolysis of the hydrazone moiety. Using the optimized conditions,
Solvent effects on the oxidative free radical reactions of 2-amino-1,4-naphthoquinones
作者:Chao-Ming Tseng、Yi-Lung Wu、Che-Ping Chuang
DOI:10.1016/j.tet.2004.10.029
日期:2004.12
Solvent effects on the manganese (III) initiatedoxidativefreeradicalreactions of 2-amino-1,4-naphthoquinones are described. This freeradicalreaction provides a novel method for the synthesis of benzo[f]indole-4,9-diones, benzo[f]indole-2,4,9-triones, benzo[b]carbazole-6,11-diones and benzo[b]acridine-6,11-diones. High chemoselectivity was observed in different solvents.
描述了溶剂对2-氨基-1,4-萘醌的锰(III)引发的氧化自由基反应的影响。该自由基反应为合成苯并[ f ]吲哚-4,9-二酮,苯并[ f ]吲哚-2,4,9-三酮,苯并[ b ]咔唑-6,11-二酮和苯并[ b ] ac啶-6,11-二酮。在不同溶剂中观察到高化学选择性。
The nitrosoDiels-Alder (NDA) reaction is an attractive strategy for the synthesis of 3,6-dihydro-1,2-oxazines and 1-amino-4-hydroxy-2-ene derivatives. Herein we report the Cu(I)-DTBM-Segphos catalyzed asymmetric intermolecular NDA reaction of variously substituted cyclic 1,3-dienes using highly reactive nitroso compounds derived from pyrimidine and pyridazine derivatives. In most of the cases studied
pharmacologically active targets. Regioselective γ-C–N bond formation is achieved with simple enone substrates through controlled dienolate reactivitytoward azodicarboxylate electrophiles. The amination reaction occurs readily with sterically demanding nucleophiles and is stereoselective.