Enantioselective Kinetic Resolution/Desymmetrization of
<i>Para</i>
‐Quinols: A Case Study in Boronic‐Acid‐Directed Phosphoric Acid Catalysis
作者:Banruo Huang、Ying He、Mark D. Levin、Jaime A. S. Coelho、Robert G. Bergman、F. Dean Toste
DOI:10.1002/adsc.201900816
日期:2020.1.23
A chiral phosphoric acid‐catalyzed kineticresolution 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
Reaction of p-substituted phenols 2 with a catalytic amount of 4-iodophenoxyacetic acid (1) and Oxone® as a co-oxidant in tetrahydrofuran (THF) or 1,4-dioxane–water gave the corresponding p-quinols 3 in excellent yields. Reaction of p-dialkoxyarenes 4 in 2,2,2-trifluoroethanol–water gave the corresponding p-quinones 5 in excellent yield without purification. These reactions provide efficient and practical
Site-selective 1,3-double functionalization of arenes using <i>para</i>-quinol, C–N, and C–C/C–P three-component coupling
作者:Saddam Husen、Anil Chauhan、Ravindra Kumar
DOI:10.1039/c9gc04103f
日期:——
A catalytic and site-selective approach has been demonstrated for dual functionalization of arenes via cross-coupling reactions of p-quinols with amines and isocyanides/phosphites.
containing furan and thiophene moieties in addition to a carbonyl group in the vicinity of the iodine atom were synthesised and characterised. The X-ray analysis of both compounds revealed a strong intramolecular contact between the carbonyl oxygen and the hypervalent iodine atom with tosylate as a counter ion. The two reagents showed a broad range of syntheticapplications and proved to be versatile oxidizing
A variety of substituted acridones were synthesized via a one-pot, metal-free cascade reaction. In this event, the DBU-mediated addition between quinols and ortho-methoxycarbonylaryl isocyanates formed a bicyclic oxazolidinone, followed by a sequence of intramolecular condensation, tautomerization, and decarboxylation, which led to the formation of acridones. The acridones showed mild activity against