Asymmetric Transformations of Acyloxyphenyl Ketones by Enzyme−Metal Multicatalysis
摘要:
A multipathway process comprising several enzyme- and metal-catalyzed reactions has been explored for the asymmetric transformations of acyloxyphenyl ketones to optically active hydroxyphenyl alcohols in the ester forms. The process comprises nine component reactions in three pathways, all of which take place by the catalytic actions of only two catalysts, a lipase and a ruthenium complex. The synthetic reactions were carried out on 0.2-0.6 mmol scales for eight different substrates under an atmosphere of hydrogen (I atm) in toluene at 70 degreesC for 3 days. In most cases, the yields were high (92-96%) and the optical purities were excellent (96-98% ee), This work thus has demonstrated that enzyme-metal multicatalysis has great potential as a new methodology for asymmetric transformations.
Iodine(V) Reagents in Organic Synthesis. Part 4. <i>o</i>-Iodoxybenzoic Acid as a Chemospecific Tool for Single Electron Transfer-Based Oxidation Processes
作者:K. C. Nicolaou、T. Montagnon、P. S. Baran、Y.-L. Zhong
DOI:10.1021/ja012127+
日期:2002.3.1
o-Iodoxybenzoic acid (IBX), a readily available hypervalent iodine(V) reagent, was found to be highly effective in carrying out oxidations adjacent to carbonyl functionalities (to form alpha,beta-unsaturated carbonyl compounds) and at benzylic and related carbon centers (to form conjugated aromatic carbonyl systems). Mechanistic investigations led to the conclusion that these new reactions are initiated
Selective Oxidation at Carbon Adjacent to Aromatic Systems with IBX
作者:K. C. Nicolaou,*、Phil S. Baran、Yong-Li Zhong
DOI:10.1021/ja004218x
日期:2001.4.1
oxidation of benzylic positions is quite general and proceeds efficiently in fluorobenzene/DMSO (2:1) or DMSO at 80 -90 °C. The reaction is not affected by the presence of water (entry 3), o-substituents (entries 4, 9, 11, 14, 17), or the presence of halogens (entries 5, 6). Over-oxidation to the corresponding carboxylicacid was not observed even in the presence of electron-rich substrates (entry 7). n-Butylbenzene
Regioselective Hydroperoxygenation of Aralkanes and α,β‐Unsaturated Carbonyl Compounds Catalyzed by<i>N</i>‐Hydroxyphthalimide and 2,2′‐Azobis(4‐methoxy‐2,4‐dimethylvaleronitrile)
Aerobic oxidation of aralkanes and alpha,beta-unsaturated carbonyl compounds in the presence of a catalytic amount of N-hydroxyphthalimide (NHPI) and 2,2'-Azobis(4-methoxy-2,4-dimethylvaleronitrile) (V-70) under 1 atmos. of oxygen at 30 degrees C gave alpha-hydroperoxyaralkanes and gamma-hydroperoxy-alpha, beta-unsaturated carbonyl compounds, respectively.