2876-03-1Relevant academic research and scientific papers
Enantioselective Kinetic Resolution/Desymmetrization of Para-Quinols: A Case Study in Boronic-Acid-Directed Phosphoric Acid Catalysis
Huang, Banruo,He, Ying,Levin, Mark D.,Coelho, Jaime A. S.,Bergman, Robert G.,Toste, F. Dean
supporting information, p. 295 - 301 (2019/11/03)
A chiral phosphoric acid-catalyzed kinetic resolution and desymmetrization of para-quinols operating via oxa-Michael addition was developed and subsequently subjected to mechanistic study. Good to excellent s-factors/enantioselectivities were obtained over a broad range of substrates. Kinetic studies were performed, and DFT studies favor a hydrogen bonding activation mode. The mechanistic studies provide insights to previously reported chiral anion phase transfer reactions involving chiral phosphate catalysts in combination with boronic acids. (Figure presented.).
Catalyst-Controlled Regiodivergent Alkyne Insertion in the Context of C?H Activation and Diels–Alder Reactions: Synthesis of Fused and Bridged Cycles
Zhou, Xukai,Pan, Yupeng,Li, Xingwei
supporting information, p. 8163 - 8167 (2017/06/30)
Rhodium(III)- and cobalt(III)-catalyzed C?H activation of indoles and coupling with 1,6-enynes is discussed. Under rhodium(III) catalysis, the alkyne insertion follows 2,1-regioselectivity with a subsequent type-I intramolecular Diels–Alder reaction (IMDA) to afford [6,5]-fused cycles. When catalyzed by the cobalt(III) congener, 1,2-insertion of the alkyne is preferred, and followed by a rare type-II IMDA, thus leading to bridged [3,3,1]-cycles. This selectivity of the alkyne insertion was mainly tuned by the steric sensitivity of the catalyst.
Tunable arylative cyclization of 1,6-enynes triggered by rhodium(III)-catalyzed C-H activation
Fukui, Yuki,Liu, Ping,Liu, Qiang,He, Zhi-Tao,Wu, Nuo-Yi,Tian, Ping,Lin, Guo-Qiang
supporting information, p. 15607 - 15614 (2014/12/11)
Two tunable arylative cyclizations of cyclohexadienone-containing 1,6-enynes are reported via rhodium(III)-catalyzed C-H activation of O-substituted N-hydroxybenzamides. The use of different O substituents, i.e. O-Piv and O-Me, on the directing group allows the formation of either tetracyclic isoquinolones through an N-Michael addition process or hydrobenzofurans through a C-Michael addition process. Mechanistic investigations of these two cascade reactions clearly indicated that the C-H bond cleavage process was involved in the turnover-limiting step. Furthermore, the cyclization products could be subjected to various transformations for elaborating the pharmaceutically and synthetically valuable potential. This is the first example of a rhodium(III)-catalyzed arylative cyclization reaction of 1,6-enynes, and the results extend the application realm of CpRhIII-catalyzed C-H activation cascade reactions.
Active site dynamics of toluene hydroxylation by cytochrome P-450
Hanzlik,Ling
, p. 3992 - 3997 (2007/10/02)
Rat liver cytochrome P-450 hydroxylates toluene to benzyl alcohol plus o-, m-, and p-cresol. Deuterated toluenes (C6D5CH3, C6D5CD3, PhCD(n)H(3-n)) were incubated under saturating conditions
