6948-68-1Relevant academic research and scientific papers
Direct deoxygenation of active allylic alcohols via metal-free catalysis
Han, Feng,Ji, Na,Liu, Qiaowen,Miao, Chengxia,Zhang, Tong,Zhuang, Hongfeng
, p. 1680 - 1689 (2022/03/02)
Direct metal-free deoxygenation of highly active allylic alcohols catalyzed by a Br?nsted acid was achieved, which avoids tedious reaction steps and eliminates metal contamination. By examining a series of Br?nsted acids, alcohols, reaction temperatures and so on, up to 94% yield was obtained with 10 mol% TsOH·H2O as the catalyst and 2 equiv. of p-methylbenzyl alcohol as the reductant at 80 °C for 2 h. The system was mainly suitable for aromatic allylic alcohols, and the yield was excellent as determined via gram-scale synthesis. The main product was double bond near the side of a more electron-rich aryl group when allylic alcohols featuring different substituents at the 1 and 3 positions were used as the substrates. Deuterium-labelled experiments clearly demonstrated that the hydrogen source was the methylene of p-methylbenzyl alcohol and other control experiments indicated the existence of two ether intermediates. Interestingly, in situ hydrogen transfer of allylic benzyl ether is a key process, but kinetic isotopic effect studies (kH/kD = 1.28) showed that the C-H bond cleavage was not the rate-determining step. A possible mechanism involving carbocations, ether intermediates and hydrogen transfer is proposed.
A photocatalyst-free photo-induced denitroalkylation of β-nitrostyrenes with 4-alkyl substituted Hantzsch esters at room temperature
Duan, Chunying,Hao, Xinyu,Jin, Kun,Li, Yaming,Wang, Jiaao,Zhang, Rong,Zhang, Siyu
, (2020/02/18)
A photocatalyst-free stereoselectively photo-induced strategy for the denitroalkylation of β-nitrostyrenes using 4-alkyl substituted Hantzsch esters as the alkyl source under xenon lamp irradiation is developed. The reaction proceeds at room temperature and affords the corresponding products in moderate to excellent yields. The oxidant di-t-butyl peroxide serves as an efficient radical initiator under irradiation of a Xenon lamp, initiating alkyl radicals from the 4-alkyl substituted Hantzsch esters.
Influences of Phenyl Rings on NHC Ligands with Bicyclic Architectures
Ando, Shin,Miyata, Ryota,Matsunaga, Hirofumi,Ishizuka, Tadao
, p. 128 - 139 (2019/01/04)
In addition to phosphanes, olefins, amines, and amides, over the past two decades N-heterocyclic carbene (NHC) has emerged as a useful alternative ligand. Based on a number of derivatization studies on NHC ligands, imidazol-2-ylidene and imidazolin-2-ylidene became the standard heterocyclic form, and bulky substituents have commonly been introduced on the nitrogen(s) adjacent to carbenic carbons. Our group previously developed NHCs equipped with noncarbenic carbons with a bicyclic architecture that gives them unique steric properties that make them bulky but accessible. In this study, we synthesized a novel type of NHC ligand that possesses a bicyclo[2.2.1]heptane architecture, and we compared five derivatives using copper-catalyzed allylic arylations with aryl Grignard reagents. The regioselectivity of the substitution obviously indicates that a phenyl ring over an active site has a characteristic effect on the resultant copper catalysts when γ-substitution is the major pathway.
Dual nickel and Lewis acid catalysis for cross-electrophile coupling: The allylation of aryl halides with allylic alcohols
Jia, Xue-Gong,Guo, Peng,Duan, Jicheng,Shu, Xing-Zhong
, p. 640 - 645 (2018/01/28)
Controlling the selectivity in cross-electrophile coupling reactions is a significant challenge, particularly when one electrophile is much more reactive. We report a general and practical strategy to address this problem in the reaction between reactive and unreactive electrophiles by a combination of nickel and Lewis acid catalysis. This strategy is used for the coupling of aryl halides with allylic alcohols to form linear allylarenes selectively. The reaction tolerates a wide range of functional groups (e.g. silanes, boronates, anilines, esters, alcohols, and various heterocycles) and works with various allylic alcohols. Complementary to most current routes for the C3 allylation of an unprotected indole, this method provides access to C2 and C4-C7 allylated indoles. Preliminary mechanistic experiments reveal that the reaction might start with an aryl nickel intermediate, which then reacts with Lewis acid activated allylic alcohols in the presence of Mn.
Photochemical Heck benzylation of styrenes catalyzed by Na[FeCp(CO)2]
Waldhart, Greyson W.,Mankad, Neal P.
supporting information, p. 171 - 174 (2015/03/05)
Iron-catalyzed Heck coupling of benzyl chlorides and styrenes proceeds under photochemical conditions using the well-known anionic complex, [FeCp(CO)2]- (Fp-), as a catalyst. The reaction likely proceeds through the established SN2 mechanism for Fp- alkylation, followed by styrene migratory insertion and β-hydride elimination steps that are enabled by photochemical CO dissociation.
Catalytic allylic arylation of cinnamyl carbonates over palladium nanoparticles supported on a thermoresponsive polymer in water
Lee, Yongwoo,Shabbir, Saira,Lee, Sinyoung,Ahn, Hyunsoek,Rhee, Hakjune
, p. 3579 - 3583 (2015/06/25)
Poly(NIPAM-co-4-VP) undergoes a phase transition at the low critical solution temperature with a change from the hydrophilic to the hydrophobic core in a hydrophilic solvent. Palladium nanoparticles supported on such a thermoresponsive polymer support were demonstrated to catalyze the Tsuji-Trost reaction for the arylation of various cinnamyl carbonates by arylboronic acids. Therefore, a protocol developed using mild reaction conditions demonstrates the recyclability of the catalyst in an eco-friendly solvent such as water.
A palladium NNC-pincer complex: An efficient catalyst for allylic arylation at parts per billion levels
Hamasaka, Go,Sakurai, Fumie,Uozumi, Yasuhiro
supporting information, p. 3886 - 3888 (2015/03/04)
Allylic arylation of allylic acetates by sodium tetraarylborates in the presence of ppb to ppm (molar) loadings of a palladium NNC-pincer complex catalyst in methanol at 50°C gave the corresponding arylated products in excellent yields. Total turnover numbers of up to 500 000 000 and turnover frequencies of up to 11 250 000 h-1 were achieved.
Copper-Catalysed Allylic Substitution Using 2,8,14,20-Tetrapentylresorcinarenyl-Substituted Imidazolium Salts
Kalo?lu, Murat,?ahin, Neslihan,Sémeril, David,Brenner, Eric,Matt, Dominique,?zdemir, ?smail,Kaya, Cemal,Toupet, Lo?c
, p. 7310 - 7316 (2015/11/25)
Unsymmetrical imidazolium salts, each having one nitrogen atom (N1) substituted by a cavity-shaped TPR group (TPR = 2,8,14,20-tetrapentylresorcinaren-5-yl), were tested in situ as proligands for the copper-catalysed allylic arylation of cinnamyl bromide w
Flow chemistry as a discovery tool to access sp2-sp3 cross-coupling reactions via diazo compounds
Tran, Duc N.,Battilocchio, Claudio,Lou, Shing-Bong,Hawkins, Joel M.,Ley, Steven V.
, p. 1120 - 1125 (2015/03/04)
The work takes advantage of an important feature of flow chemistry, whereby the generation of a transient species (or reactive intermediate) can be followed by a transfer step into another chemical environment, before the intermediate is reacted with a coupling partner. This concept is successfully applied to achieve a room temperature sp2-sp3 cross coupling of boronic acids with diazo compounds, these latter species being generated from hydrazones under flow conditions using MnO2 as the oxidant.
FeCl3·6H2O-catalyzed selective reduction of allylic halides to alkenes with concomitant oxidation of benzylic alcohols to aldehydes
Zhang, Houcai,Liu, Ruiting,Zhou, Xigeng
, p. 282 - 288 (2014/03/21)
Iron-catalyzed direct reduction of allylic halides with benzylic alcohol was achieved, providing a new, simple, and efficient method for conducting highly regioselective hydrodehalogenation. This method not only features a readily available reductant, an
