130633-06-6Relevant academic research and scientific papers
Practical synthesis of aromatic bisabolanes: Synthesis of 1,3,5-bisabolatrien-7-ol, peniciaculin A and B, and hydroxysydonic acid
Ishigami, Ken,Katsuta, Ryo,Murakawa, Hazuki,Saito, Tatsuo,Shiotani, Nanami,Shirakawa, Izumi,Ueda, Kazuya,Yajima, Arata
supporting information, (2021/06/12)
The enantioselective synthesis of aromatic bisabolanes, such as 1,3,5-bisabolatrien-7-ol, peniciaculin A and B, and hydroxysydonic acid, has been described. Our methodology for the total synthesis of aromatic bisabolanes involves the stereoselective const
Carbene-Catalyzed Formal [3+3] Cycloaddition Reaction for Access to Substituted 2-Phenylbenzothiazoles
Ni, Zhibin,Mou, Chengli,Zhu, Xun,Qi, Puying,Yang, Song,Chi, Yonggui Robin,Jin, Zhichao
supporting information, p. 492 - 495 (2020/01/24)
A carbene-catalyzed oxidative cycloaddition reaction is developed for efficient access to multi-functionalized 2-phenylbenzothiazoles. A broad scope of heavily substituted arenes bearing 2-benzothiazole groups have been prepared in good to excellent yields. The remote C(sp2)–H bond in the substituted arene products can be activated by Pd catalysts in regio-selective fashion with the direction of the 2-benzothiazole groups.
NHC-catalyzed asymmetric α-regioselective [4 + 2] annulation to construct α-alkylidene-δ-lactones
Liu, Lala,Guo, Donghui,Wang, Jian
supporting information, p. 7025 - 7029 (2020/09/15)
The unprecedented NHC-catalyzed [4 + 2] annulation of α-bromoenals with dioxopyrrolidines is described. This protocol features broad substrate scope and allows rapid assembly of α-alkylidene-δ-lactones in good to high yields with excellent enantioselectivities. Notably, this process includes α-regioselective activation of azolium dienolate intermediates, which has not yet been reported.
Highly Selective and Catalytic Generation of Acyclic Quaternary Carbon Stereocenters via Functionalization of 1,3-Dienes with CO2
Chen, Xiao-Wang,Zhu, Lei,Gui, Yong-Yuan,Jing, Ke,Jiang, Yuan-Xu,Bo, Zhi-Yu,Lan, Yu,Li, Jing,Yu, Da-Gang
, p. 18825 - 18835 (2019/11/28)
The catalytic asymmetric functionalization of readily available 1,3-dienes is highly important, but current examples are mostly limited to the construction of tertiary chiral centers. The asymmetric generation of acyclic products containing all-carbon quaternary stereocenters from substituted 1,3-dienes represents a more challenging, but highly desirable, synthetic process for which there are very few examples. Herein, we report the highly selective copper-catalyzed generation of chiral all-carbon acyclic quaternary stereocenters via functionalization of 1,3-dienes with CO2. A variety of readily available 1,1-disubstituted 1,3-dienes, as well as a 1,3,5-triene, undergo reductive hydroxymethylation with high chemo-, regio-, E/Z-, and enantioselectivities. The reported method features good functional group tolerance, is readily scaled up to at least 5 mmol of starting diene, and generates chiral products that are useful building blocks for further derivatization. Systemic mechanistic investigations using density functional theory calculations were performed and provided the first theoretical investigation for an asymmetric transformation involving CO2. These computational results indicate that the 1,2-hydrocupration of 1,3-diene proceeds with high π-facial selectivity to generate an (S)-allylcopper intermediate, which further induces the chirality of the quaternary carbon center in the final product. The 1,4-addition of an internal allylcopper complex, which differs from previous reports involving terminal allylmetallic intermediates, to CO2 kinetically determines the E/Z- and regioselectivity. The rapid reduction of a copper carboxylate intermediate to the corresponding silyl-ether in the presence of Me(MeO)2SiH provides the exergonic impetus and leads to chemoselective hydroxymethylation rather than carboxylation. These results provide new insights for guiding further development of asymmetric C-C bond formations with CO2
Carbene-catalyzed enal γ-carbon addition to α-ketophosphonates for enantioselective access to bioactive 2-pyranylphosphonates
Sun, Jun,He, Fangcheng,Wang, Zhongyao,Pan, Dingwu,Zheng, Pengcheng,Mou, Chengli,Jin, Zhichao,Chi, Yonggui Robin
supporting information, p. 6040 - 6043 (2018/06/18)
A carbene-catalyzed enantioselective [4+2] cycloaddition reaction between α,β-unsaturated aldehydes and α-ketophosphonates is developed. The reaction affords chiral 2-pyranylphosphonates with excellent enantioselectivities. The optically enriched phosphonate products bear multiple functional groups, including unsaturated lactone and phosphonate moieties that often lead to unique bio-activities. Preliminary studies show that the products from our reactions exhibit anti-bacterial (X. oryzae pv. oryzae) and anti-viral (Tobacco Mosaic Virus) activities for potential use in plant protection.
Rh-Catalyzed Asymmetric Hydrogenation of β-Branched Enol Esters for the Synthesis of β-Chiral Primary Alcohols
Liu, Chong,Yuan, Jing,Zhang, Jian,Wang, Zhihui,Zhang, Zhenfeng,Zhang, Wanbin
supporting information, p. 108 - 111 (2018/01/17)
An asymmetric hydrogenation of β-branched enol esters has been developed for the first time, providing a new route for the synthesis of β-chiral primary alcohols. Using a (S)-SKP-Rh complex bearing a large bite angle and enol ester substrates possessing an O-fomyl directing group, the desired products were obtained in quantitative yields and with excellent enantioselectivities.
Selective Hydroarylation of 1,3-Diynes Using a Dimeric Manganese Catalyst: Modular Synthesis of Z-Enynes
Yan, Zhongfei,Yuan, Xiang-Ai,Zhao, Yue,Zhu, Chengjian,Xie, Jin
supporting information, p. 12906 - 12910 (2018/09/25)
The transition-metal-catalyzed selective hydroarylation of unsymmetrical alkynes represents the state-of-art in organic chemistry, and still mainly relies on the use of precious late-transition-metal catalysts. Reported herein is an unprecedented MnI-catalyzed hydroarylation of unsymmetrical 1,3-diyne alcohols with commercially available arylboronic acids with predictive selectivity. This method addresses the challenges in regio-, stereo-, and chemoselectivity. It offers a general, convenient and practical strategy for the modular synthesis of multisubstituted Z-configurated conjugated enynes. This protocol is distinguished by its operational simplicity, complete selectivity, excellent functional-group compatibility, and gram-scale potential. A dimeric MnI species, Mn2(CO)8Br2, was proven to be a much more efficient catalyst precursor than Mn(CO)5Br.
Transition-Metal-Free Formylation of Allylzinc Reagents Leading to α-Quaternary Aldehydes
Haraguchi, Ryosuke,Kusakabe, Akinori,Mizutani, Nakaba,Fukuzawa, Shin-Ichi
supporting information, p. 1613 - 1616 (2018/03/23)
The first example of formylation of allylzinc reagents using S-phenyl thioformate is presented. The reaction proceeded under mild conditions without any transition-metal catalyst, forming quaternary carbon centers with reactive functionalities, such as formyl and vinyl groups. Moreover, Barbier-type formylation of an allylic bromide with a sterically demanding thioformate was achieved. As a preliminary result, asymmetric formylation was conducted using a menthol-derived chiral thioformate.
Iminium Catalysis inside a Self-Assembled Supramolecular Capsule: Scope and Mechanistic Studies
Br?uer, Thomas M.,Zhang, Qi,Tiefenbacher, Konrad
supporting information, p. 17500 - 17507 (2017/12/15)
Although iminium catalysis has become an important tool in organic chemistry, its combination with supramolecular host systems has remained largely unexplored. We report the detailed investigations into the first example of iminium catalysis inside a supramolecular host. In the case of 1,4-reductions of α,β-unsaturated aldehydes, catalytic amounts of host are able to increase the enantiomeric excess of the products formed. Several control experiments were performed and provided strong evidence that the modulation of enantiomeric excess of the reaction product indeed stems from a reaction on the inside of the capsule. The origin of the increased enantioselectivity in the capsule was investigated. Furthermore, the substrate and nucleophile scope were studied. Kinetic investigations as well as the kinetic isotope effect measured confirmed that the hydride delivery to the substrate is the rate-determining step inside the capsule. The exploration of benzothiazolidines as alternative hydride sources revealed an unexpected substitution effect of the hydride source itself. The results presented confirm that the noncovalent combination of supramolecular hosts with iminium catalysis is opening up new exciting possibilities to increase enantioselectivity in challenging reactions.
Green and Rapid Access to Benzocoumarins via Direct Benzene Construction through Base-Mediated Formal [4+2] Reaction and Air Oxidation
Mou, Chengli,Zhu, Tingshun,Zheng, Pengcheng,Yang, Song,Song, Bao-An,Chi, Yonggui Robin
supporting information, p. 707 - 712 (2016/03/09)
Benzocoumarin is an important structural motif widely found in natural products and synthetic molecules. Traditional methods for the synthesis of benzocoumarins and their derivatives require multiple steps, typically with an intramolecular ester forming reaction to make the lactone ring as the last step. Another major method involves transition metal-catalyzed coupling or carbon-hydrogen bond activation reactions starting with pre-existing aryl frameworks in the substrates. Here we report a new strategy for the green and rapid access to benzocoumarins and their derivatives. Our method uses readily available unsaturated aldehydes and coumarins as the substrates and air as the green oxidant. The overall reaction proceeds through a formal [4+2] process to construct a new benzene ring and thus to afford benzocoumarins in essentially a single step. No metal catalysts were used; no toxic or expensive reagents were involved. The power of our new approach is further demonstrated in a concise formal total synthesis of cannabinol, a bioactive natural product.
