28077-64-7Relevant academic research and scientific papers
Manganese-catalyzed synthesis of cis-β-amino acid esters through organometallic C-H activation of ketimines
Liu, Weiping,Zell, Daniel,John, Michael,Ackermann, Lutz
, p. 4092 - 4096 (2015)
Manganese-catalyzed C-H functionalization reactions of ketimines set the stage for the expedient synthesis of cis-β-amino acid esters through site- and regioselective alkene annulations. The organometallic C-H activation occurred efficiently with high fun
POLYMERIZATIONS OF ACETYLENES AND CYCLIC OLEFINS INDUCED BY METAL CARBYNES.
Katz,Shih,Ying,Stuart
, p. 2659 - 2668 (1984)
trans-Bromotetracarbonyl(phenylmethylidyne)tungsten and related metal carbynes induce acetylenes and cycloalkenes to polymerize. The acetylenes include examples that are monosubstituted, disubstituted, and unsubstituted, as well as the first reported functionalized acetylenes in which the functional groups (the nitrile, ester, and halogen functions were studied) are not attached to the triple bond. The cycloalkenes yield polyalkenamers whose double bonds are largely cis. This last polymerization is speeded by the presence of oxygen. The stereochemistries of the polyacetylenes and the polynorbornenamer produced when the initiator is the metal carbyne are similar to those of the polymers produced when the initiator is pentacarbonyl(methoxyphenylmethylene)tungsten. A possible mechanism is presented to account for why the metal carbynes behave as though they were sources of reactive metal carbenes.
CONFORMATIONAL ORDER IN CRYSTALLINE STATES AND GELS OF ISOTACTIC, SYNDIOTACTIC AND ATACTIC POLYSTYRENES STUDIED BY VIBRATIONAL SPECTROSCOPY
Nakaoki, Takahiko,Kobayashi, Masamichi
, p. 315 - 331 (1991)
Stable conformations and their sequential order of isotactic (IPS), syndiotactic (SPS) and atactic polystyrenes (APS) in various aggregation states have been investigated by infrared (IR) spectroscopy, 13C NMR and X-ray diffraction.It has been demonstrated that the partially ordered skeletal conformation existing in IPS/CS2 gels of a (3/1) helix (TG) type having the pendant phenyl groups oriented in a disordered fashion, rather than the near-TT form proposed previously for IPS/decalin gels.The process of conformational change during gelation of IPS/CS2 and APS/CS2 systems has been followed by IR spectroscopy, and it has been concluded that the construction of regular sequences of a particular conformation promotes the gelation of both crystallizable and non-crystallizable polystyrenes.As-cast film specimens prepared from a chloroform solution are found to be a crystalline polymer-solvent complex (the γ phase) having a TTGG conformation.On heating, the γ phase transforms to a β phase at about 120 deg C, accompanied by removal of the solvent, while the TTGG conformation is retained.On further heating, the β phase transforms to an α1 or α2 phase at about 200 deg C accompanied by a change in conformation from TTGG to TT.The process of conformational change (in both type and sequence) during these phase transformations has been clarified by IR spectroscopy.
Synthesis of Substituted 1-Hydroxy-2-Naphthaldehydes by Rhodium-Catalyzed C?H Bond Activation and Vinylene Transfer of Enaminones with Vinylene Carbonate
Liu, Min,Yan, Kelu,Wen, Jiangwei,Liu, Weihua,Wang, Mingyu,Wang, Lina,Wang, Xiu
supporting information, p. 512 - 517 (2021/12/09)
The rhodium(III)-catalyzed C?H bond activation and vinylene transfer of enaminones with vinylene carbonate have been proposed for the synthesis of substituted 1-hydroxy-2-naphthaldehydes in 49–84% yields. Several preliminary mechanistic studies and hydrox
Rhodium-Catalyzed Annulation of Phenacyl Ammonium Salts with Propargylic Alcohols via a Sequential Dual C-H and a C-C Bond Activation: Modular Entry to Diverse Isochromenones
Nanubolu, Jagadeesh Babu,Reddy Singam, Maneesh Kumar,Sridhar Reddy, Maddi,Suresh, Vavilapalli,Suri Babu, Undamatla
supporting information, p. 7888 - 7893 (2021/10/25)
Given their omnipresence in natural products and pharmaceuticals, isochromenone congeners are one of the most privileged scaffolds to synthetic chemists. Disclosed herein is a dual (ortho/meta) C-H and C-C activation of phenacyl ammonium salts (acylammonium as traceless directing group) toward annulation with propargylic alcohols to accomplish rapid access for novel isochromenones by means of rhodium catalysis from readily available starting materials. This operationally simple protocol features broad substrate scope and wide functional group tolerance. Importantly, the protocol circumvents the need of any stoichiometric metal oxidants and proceeds under aerobic conditions.
Experimental and Computational Studies of Palladium-Catalyzed Spirocyclization via a Narasaka-Heck/C(sp3or sp2)-H Activation Cascade Reaction
Wei, Wan-Xu,Li, Yuke,Wen, Ya-Ting,Li, Ming,Li, Xue-Song,Wang, Cui-Tian,Liu, Hong-Chao,Xia, Yu,Zhang, Bo-Sheng,Jiao, Rui-Qiang,Liang, Yong-Min
supporting information, p. 7868 - 7875 (2021/05/27)
The first synthesis of highly strained spirocyclobutane-pyrrolines via a palladium-catalyzed tandem Narasaka-Heck/C(sp3 or sp2)-H activation reaction is reported here. The key step in this transformation is the activation of a δ-C-H bond via an in situ generated σ-alkyl-Pd(II) species to form a five-membered spiro-palladacycle intermediate. The concerted metalation-deprotonation (CMD) process, rate-determining step, and energy barrier of the entire reaction were explored by density functional theory (DFT) calculations. Moreover, a series of control experiments was conducted to probe the rate-determining step and reversibility of the C(sp3)-H activation step.
Rhodium-Catalyzed Spiro Indenyl Benzoxazine Synthesis via C-H Activation/Annulation of 3-Aryl-2H-Benzo[b][1,4]oxazines and Alkynes
Tan, Heng,Laishram, Ronibala Devi,Zhang, Xuexin,Shi, Guangrui,Li, Kangkui,Chen, Jingchao
supporting information, p. 4542 - 4546 (2020/07/04)
The rhodium (III)-catalyzed annulation of 3-Aryl-2H-Benzo[b][1,4]oxazines with alkynes via C–H activation has been developed. This reaction afforded a series of spiro indenyl benzoxazine in high yields under mild reaction condition with good functional group tolerance.
Rh(III)-catalyzed synthesis of isoquinolines using the N-Cl bond of N-chloroimines as an internal oxidant
Chu, Benfa,Fang, Lili,Guo, Shan,Qi, Bing,Shi, Pengfei,Wang, Qi,Zhu, Jin
supporting information, (2020/03/10)
The Rh(III)-catalyzed coupling of N-chloroimines with alkynes for the efficient synthesis of isoquinolines is reported. This represents the first use of the N-Cl bond of N-chloroimines as an internal oxidant for construction of the isoquinoline skeleton. The synthesis features atom and step economy, a green solvent (EtOH), mild reaction conditions, and a broad substrate scope.
Hydroxylamine-O-Sulfonic Acid (HOSA) as a Redox-Neutral Directing Group: Rhodium Catalyzed, Additive Free, One-Pot Synthesis of Isoquinolines from Arylketones
Biswal, Pragati,Pati, Bedadyuti Vedvyas,Chebolu, Rajesh,Ghosh, Asit,Ravikumar
supporting information, p. 1006 - 1014 (2020/02/15)
A new application of hydroxylamine-O-sulfonic acid (HOSA) has been discovered whereby aromatic ketones react with HOSA and alkynes to form isoquinolines in the presence of a RhIII catalyst. This C–H/N–O annulation methodology gives excellent yields even without any silver additive, acid/base or metal oxidant. This is the first report wherein a directing group is simultaneously forming in situ, acting as acid additive, and also as an internal oxidant.
Rhodium-catalyzed C–H activation/cyclization of enaminones with sulfoxonium ylides toward polysubstituted naphthalenes
Wang, Zhenlian,Xu, Huang
supporting information, p. 664 - 667 (2019/02/06)
A rhodium-catalyzed ortho-C–H functionalization and annulation between enaminones and sulfoxonium ylides was developed, affording a series of multi-substituted naphthalenes in good to moderate yields with excellent functional group compatibility. The proc
