Hydroxyl-directed C–C bond activation of benzophenones for the O-acylation of phenols
作者:Constance B. Anderson、Siri Bruhn、Letitia J. Yao、Christopher J. Douglas
DOI:10.1016/j.tet.2022.133074
日期:2022.12
We report that 2-hydroxyl benzophenones can be converted to phenyl salicylate esters by loss of an aryl group and O-acylation of the phenols. Iridium, cyclooctadiene, and bulky monodentate phosphine ligands catalyze the ketone C–C bond activation and fragmentation. We identified common side products in this process, which include C-acylation of the phenol reactant or trapping on cyclooctadiene. Several
Schoepff, Chemische Berichte, 1892, vol. 25, p. 3644
作者:Schoepff
DOI:——
日期:——
Singularity analysis of geometric constraint systems
作者:Xiaobo Peng、Liping Chen、Fanli Zhou、Ji Zhou
DOI:10.1007/bf02947309
日期:2002.5
Singularity analysis is an important subject of the geometric constraint satisfaction problem. In this paper, three kinds of singularities are described and corresponding identification methods are presented for both under-constrained systems and over-constrained systems. Another special but common singularity for under-constrained geometric systems, pseudo-singularity, is analyzed. Pseudo-singularity is caused by a variety of constraint matching of under-constrained systems and can be removed by improving constraint distribution. To avoid pseudo-singularity and decide redundant constraints adaptively, a differentiation algorithm is proposed in the paper. Its correctness and efficiency have been validated through its practical applications in a 2D/3D geometric constraint solver CBA.
Rhodium-Catalyzed Carbonylative Synthesis of Aryl Salicylates from Unactivated Phenols
A rhodium-catalyzed carbonylative transformation of unactivated phenols to arylsalicylates is described. This protocol is characterized by utilizing 1,3-rhodium migration as the key step to provide direct access to synthesize o-hydroxyaryl esters. Various desired aryl o-hydroxybenzoates were produced in moderate to excellent yields with bis(dicyclohexylphosphino)ethane (DCPE) as the ligand. Interestingly
A direct synthesis of salicylic acid chlorides is achieved via "metal-driven" intracomplex acylation of bromomagnesium and aluminum phenoxides with phosgene. Salicylic acids 5 and some derivatives 6, 7 can be obtained by quenching the reaction mixture with convenient reagents. Moreover the reaction of lithium phenylacetylide with 3 provides a new convenient approach to ortho-hydroxyaryl alkynyl ketones like 8. The oriented complex 2, involving the metal phenoxide and phosgene is proposed to account for the ortho-regioselective control of the reaction.