Predicted outcomes: The additionreaction of organoboronicacids with aldehydes in the presence of K2CO3 catalyzed by CoI2/(R,R)‐BDPP gives chiral secondary alcohols in excellent yields with 90–99 % enantiomeric excess (see scheme; (R,R)‐BDPP=(2R,4R)‐(+)‐2,4‐bis(diphenylphosphino)pentane). This method provides an alternative to prepare an R and S enantiomeric pair by using the same chiral ligand and
预期的结果:在CoI 2 /(R,R)-BDPP催化下,在存在K 2 CO 3的情况下,有机硼酸与醛的加成反应可得到出色的手性仲醇,对映体过量90-99%(参见方案;(R,R)-BDPP =(2 R,4 R)-(+)-2,4-双(二苯基膦基)戊烷)。该方法提供了另一种通过使用相同的手性配体制备R和S对映体对的方法,并且可以预测反应的立体化学结果。
Rhodium-Catalyzed Aldehyde Arylation via Formate-Mediated Transfer Hydrogenation: Beyond Metallic Reductants in Grignard/Nozaki–Hiyami–Kishi-Type Addition
作者:Robert A. Swyka、Wandi Zhang、Jeffery Richardson、J. Craig Ruble、Michael J. Krische
DOI:10.1021/jacs.8b13652
日期:2019.2.6
intermolecular carbonyl arylations via transferhydrogenative reductive coupling are described. Using rhodium catalysts modified by tBu2PMe, sodium formate-mediated reductive coupling of aryl iodides with aldehydes occurs in a chemoselective fashion in the presence of protic functional groups and lower halides. This work expands the emerging paradigm of transferhydrogenative coupling as an alternative to pre-formed
Nickel-Catalyzed Addition of Aryl Bromides to Aldehydes To Form Hindered Secondary Alcohols
作者:Kevin J. Garcia、Michael M. Gilbert、Daniel J. Weix
DOI:10.1021/jacs.8b13709
日期:2019.2.6
Transition-metal-catalyzed addition of aryl halides across carbonyls remains poorly developed, especially for aliphatic aldehydes and hindered substrate combinations. We report here that simple nickel complexes of bipyridine and PyBox can catalyze the addition of aryl halides to both aromatic and aliphatic aldehydes using zinc metal as the reducing agent. This convenient approach tolerates acidic functional
Activation of Functional Arylzincs Prepared from Aryl Iodides and Highly Enantioselective Addition to Aldehydes
作者:Albert M. DeBerardinis、Mark Turlington、Lin Pu
DOI:10.1021/ol8008478
日期:2008.7.3
An easily available chiral ligand ( S)- 1 is found to activate the nucleophilic reaction of the arylzincs prepared in situ from the reaction of aryl iodides with Et(2)Zn. Both high yields and high enantioselectivity (up to >99% ee) for the reaction of these arylzincs with a variety of aldehydes are obtained. The mild reaction conditions and the good functional group tolerance make this catalytic asymmetric
Arylation and alkenylation of aromatic aldehydes with silanediols is shown to proceed by use of a catalytic amount of rhodium complex. Treatment of ethyl(4-methoxyphenyl)silanediol with benzaldehyde in the presence of 3 mol% of [Rh(OH)(cod)]2 affords 4-methoxyphenyl(phenyl)methanol in 59% yield after stirring at 70 °C for 24 hours. On the other hand, diarylketone was also obtained at elevated temperature via β-hydride elimination from intermediary rhodium alkoxide.