Direct C–C Bond Formation of Allylic Alcohols with CO<sub>2</sub> toward Carboxylic Acids by Photoredox/Nickel Dual Catalysis
作者:Zhengning Fan、Shenhao Chen、Song Zou、Chanjuan Xi
DOI:10.1021/acscatal.2c00418
日期:2022.3.4
Carboxylation of allylic alcohols with carbondioxide is accomplished by photoredox/nickel dual catalysis, generating linear acids exclusively with good Z/E stereoselectivity. Hantzsch ester is employed as the reductant instead of stoichiometric metallic reductants, and the reaction can be conducted under room temperature with a blue LED light source. Mechanisticstudies reveal that the presence of
烯丙醇与二氧化碳的羧基化是通过光氧化还原/镍双重催化完成的,仅生成具有良好Z/E立体选择性的线性酸。采用 Hantzsch 酯代替化学计量的金属还原剂作为还原剂,反应可以在室温下用蓝色 LED 光源进行。机理研究表明,该催化体系中水的存在对反应的成功至关重要,并且反应更有可能在原位形成的烯丙基碳酸氢盐的氧化加成中进行。
Polymerization. XII. The Metalation of Olefins and Dienes and their Use in Alfin Polymerization of Butadiene<sup>1</sup>
作者:Avery A. Morton、Frank D. Marsh、Robert D. Coombs、Anne L. Lyons、Siegfried E. Penner、Hugh E. Ramsden、Vernon B. Baker、Ernest L. Little、Robert L. Letsinger
DOI:10.1021/ja01164a125
日期:1950.8
Benner, Jill P.; Gill, G. Bryon; Parrott, Stephen J., Journal of the Chemical Society. Perkin transactions I, 1984, # 3, p. 331 - 342
作者:Benner, Jill P.、Gill, G. Bryon、Parrott, Stephen J.、Wallace, Brian
DOI:——
日期:——
(Z)-.alpha.-(trimethylsilyl) .alpha.,.beta.-unsaturated esters. Their stereoselective conversion into .alpha.,.beta.- and .beta.,.gamma.-unsaturated esters and .beta.,.gamma.-unsaturated ketene acetals
作者:M. Ramin Najafi、Mei Ling Wang、George Zweifel
DOI:10.1021/jo00007a039
日期:1991.3
Deprotonation of methyl (Z)-alpha-(trimethylsilyl) alpha,beta-unsaturated esters with lithium diisopropylamide (LDA) or with lithium hexamethyldisilazide (LHMDS) in the presence of hexamethylphosphoramide (HMPA) as an activator, followed by protonation of the intermediate dienolates with methanol, produces stereoselectively the desilylated (E)-3-alkenoic esters. Trapping the dienolates with chlorotrimethylsilane instead of methanol and then treatment of the resultant ketene acetals with aqueous hydrochloric acid affords (E)-alpha-(trimethylsilyl)-beta,gamma-alkenoic esters in 98% isomeric purities. In the absence of HMPA, (Z)-alpha-(trimethylsilyl)-alpha, beta-alkenoic esters undergo a Michael-type addition with LDA to furnish, after methanol-mediated elimination of the diisopropylamine moiety, (E)-alpha-(trimethylsilyl)-alpha,beta-alkenoic esters. In contrast to the behavior with the corresponding Z esters, deprotonation of the E esters with LDA does not require an activator. Treatment of the dienolate intermediates formed with chlorotrimethylsilane yields (O-methyl-C,O-bis(trimethylsilyl)ketene acetals, and alkylation furnishes (E)-alpha-alkyl beta,gamma-unsaturated esters. Protodesilylation of the latter compounds with tetra-n-butylammonium fluoride followed by hydrolytic workup provides trisubstituted 2-alkenoates.
Ruthenium Complex-Catalyzed Carbonylation of Allylic Compounds
Allylic alkyl carbonates are carbonylated under 40 atm of carbon monoxide at 100-120 degrees C in the presence of a catalytic amount of Ru-3(CO)(12)/1,10-phenanthroline to give alpha,beta- or beta,gamma-unsaturated esters in good to high yields. For example, cinnamyl methyl carbonate afforded the corresponding beta,gamma-unsaturated esters, methyl trans-4-phenyl-3-butenoate (1). in 93% yield. The regioselectivity in the carbonylation of crotyl methyl carbonate is unusual and it depends on the carbon monoxide pressure. The more sterically hindered carbon (gamma-carbon) is predominantly carbonylated at 20-50 atm. When the reaction of cinnamyl methyl carbonate was performed at elevated temperature (150 degrees C) without 1,10-phenanthroline, the dimer of 1, dimethyl 3-benzyl-2-(trans-2-phenylvinyl)glutarate, was obtained in 56% yield. In the presence of secondary amines, allylic alkyl carbonates were carbonylated mainly at alpha-carbon to give alpha,beta- or beta,gamma-unsaturated amides in high yields.