Reduction with Samarium(0). Debromination of<i>vic</i>-Dibromides to Alkenes
作者:Reiko Yanada、Kiyoshi Bessho、Kazuo Yanada
DOI:10.1246/cl.1994.1279
日期:1994.7
Three electrons from Sm(0) to Sm(III) can be available during the title reduction which was achieved in 90–95% yield with vic-dibromides such as trans-10,11-dibromodibenzosuberone, meso- and dl-1,2-dibromo-1,2-diphenylethane, ethyl 2,3-dibromo-3-phenylpropionate, 2,3-dibromo-3-phenylpropionic acid, and cholesterol dibromide. These reductions were accelerated with a catalytic amount of acid.
Dimethyl Sulfoxide Mediated Elimination Reactions in 3-Aryl 2,3-Dihalopropanoates: Scope and Mechanistic Insights
作者:Wei Li、Jianchang Li、Melissa Lin、Sumrit Wacharasindhu、Keiko Tabei、Tarek S. Mansour
DOI:10.1021/jo070217c
日期:2007.8.1
Dimethyl sulfoxide (DMSO) efficiently causes the reductive elimination of 3-aryl 2,3-dibromopropanoates to cinnamates with good yield. With 3-phenyl 2,3-dihalopropanoates, debromination is the major pathway providing 3-phenylacrylate derivatives in high yields, whereas dehydrobromination is a competing pathway with thiophene derivatives. 1H NMR, 81Br NMR, and MS techniques indicated the formation of
二甲基亚砜(DMSO)有效地导致3-芳基2,3-二溴丙酸酯的还原消除为肉桂酸酯,收率良好。对于3-苯基2,3-二卤代丙酸酯,脱溴是提供高收率的3-苯基丙烯酸酯衍生物的主要途径,而脱氢溴化是与噻吩衍生物竞争的途径。1 H NMR,81 Br NMR和MS技术表明,在该转化过程中形成了副产物溴化DMSO,MeBr和HBr,没有证据表明形成了Br 2。DMSO作为亲核试剂和溴清除剂的双重作用解释了该反应中形成的产物。
Synthesis of 11,12-Didehydrodibenzo[a,e]cycloocten-5(6H)-one: A Strained Eight-Membered Alkyne
作者:Rolf Gleiter、Stefan Kornmayer、Frank Rominger
DOI:10.1055/s-0029-1217404
日期:2009.8
developed. The structure of 10 was assigned by spectroscopic means and confirmed by X-ray analysis of its 2,4-dinitrophenylhydrazone derivative. Reaction of the triple bond of 10 with dicarbonyl(η5-cyclopentadienyl)cobalt or dicarbonyl(η5-pentamethylcyclopentadienyl)cobalt gave the corresponding metal-stabilized cyclobutadiene complexes. alkynes - cycloadditions - eliminations - oxidations - ring expansion
Sterically hindered 5,11-dicarbo analogs of clozapine as potential chiral antipsychotic agents
作者:J. Howard Rupard、Tomas De Paulis、Aaron Janowsky、Howard E. Smith
DOI:10.1021/jm00130a006
日期:1989.10
reside in one enantiomer of the analogue whereas other unwanted biological effects of clozapine may be caused by the other enantiomer. Variable-temperature proton nuclear magnetic resonance studies showed that although 5-methylene-10-(4-methylpiperazino)-5H-dibenzo[a,d]cycloheptene exists at room temperature as configurationalenantiomers, the activation energy for thermalracemization is 19 kcal mol-1
The Synthesis of Novelp-Quinone Methides:O-Dealkylation of5-(p-Alkyloxyaryl)-10,11-dihydrodibenzo[a,d]cyclohepten-5-ols and Related Compounds
作者:Benjamin Taljaard、Jana H. Taljaard、Christopher Imrie、Mino R. Caira
DOI:10.1002/ejoc.200400754
日期:2005.6
The synthesis of a series of novel tricyclic p-quinone methides (p-QMs) from 5-(p-alkyloxyaryl)-10,11-dihydrodibenzo[a,d]cyclohepten-5-ol and related substrates in moderate-to-good yields is reported. The reaction is proposed to proceed under mild acidic conditions by O-dealkylation of the p-alkoxy group on the p-position of the pendant 5-aryl ring on the B-ring of the tricyclic system.The effect of