在该组先前开发的手性配体存在下,Pd 催化的烯醇烯丙基碳酸酯重组为烯丙基化酮是不对称的。使用 2-甲基环己酮,不对称区域选择性烷基化发生在更多取代的碳上,而没有多烷基化的并发症。在茚满酮和苯并苯酮中产生四元中心的烷基化发生的 ee 比使用锡或烯醇锂高得多。四氢萘酮中的对映诱导意义与烯醇化锡和锂的例子相反。第一次,在高 ee (78-99%) 的情况下,第三中心的不对称创建发生了。该反应与使用锂或烯醇锡之间的不同结果表明可能涉及不同的机制。
describe a general and efficient protocol for the synthesis of organophosphine compounds from phenols and phosphines (R2PH) via a metal-free C–O bond cleavage and C–P bond formation process. This approach exhibits broad substrate scope and excellent functional group tolerance. The synthetic utilities of this protocol were demonstrated by the synthesis of chiral ligands via the various transformations
The Inner-Sphere Process in the Enantioselective Tsuji Allylation Reaction with (<i>S</i>)-<i>t</i>-Bu-phosphinooxazoline Ligands
作者:John A. Keith、Douglas C. Behenna、Justin T. Mohr、Sandy Ma、Smaranda C. Marinescu、Jonas Oxgaard、Brian M. Stoltz、William A. Goddard
DOI:10.1021/ja070516j
日期:2007.10.1
We propose an inner-sphere mechanism explaining the unique performance of the Tsuji asymmetrical allylation reaction using hard prochiral enolate nucleophiles and non-prochiral allyl groups. Using first principles quantum mechanics (B3LYP density functional theory), we find that the pathway for this reaction involves nucleophilic attack followed by interconversion from a five-coordinate Pd complex
Enantioselective, catalytic allylation of ketones and olefins
申请人:Behenna C. Douglas
公开号:US20060084820A1
公开(公告)日:2006-04-20
Compounds containing a substituted or unsubstituted allyl group directly bound to a chiral carbon atom are prepared enantioselectively. Starting reactants are either chiral or achiral, and may or may not contain an attached allyloxycarbonyl group as a substituent. Chiral ligands are employed, along with transition metal catalysts. The methods of the invention are effective in providing enantioconvergent allylation of chiral molecules.
Unexpected effect of the fluorine atom on the optimal ligand-to-palladium ratio in the enantioselective Pd-catalyzed allylation reaction of fluorinated enol carbonates
The enantioselective Pd-catalyzed allylation reaction of fluorinated allyl enol carbonates is presented; a key feature of this transformation is the important effect of the ligand-to-palladium ratio on the enantioselectivity of the α-fluoroketones, since using a ligand excess (L/Pd ratio = 1.25 : 1) led to moderate results (30–76% ee), while using a L/Pd ratio <1 : 1.67 (to as low as 1 : 4) allowed the desired products to be obtained with high enantiopurity (up to 94% ee).
Regio- and Enantioselective Pd-Catalyzed Allylic Alkylation of Ketones through Allyl Enol Carbonates
作者:Barry M. Trost、Jiayi Xu
DOI:10.1021/ja043472c
日期:2005.3.9
ketones occurs asymmetrically in the presence of chiral ligands previously developed in this group. With 2-methylcyclohexanone, asymmetric regioselective alkylation occurs at the more substituted carbon without complications of polyalkylation. Alkylation to create quaternary centers in indanones and benzonabenone occurs in much higher ee than using tin or lithiumenolates. The sense of enantioinduction in
在该组先前开发的手性配体存在下,Pd 催化的烯醇烯丙基碳酸酯重组为烯丙基化酮是不对称的。使用 2-甲基环己酮,不对称区域选择性烷基化发生在更多取代的碳上,而没有多烷基化的并发症。在茚满酮和苯并苯酮中产生四元中心的烷基化发生的 ee 比使用锡或烯醇锂高得多。四氢萘酮中的对映诱导意义与烯醇化锡和锂的例子相反。第一次,在高 ee (78-99%) 的情况下,第三中心的不对称创建发生了。该反应与使用锂或烯醇锡之间的不同结果表明可能涉及不同的机制。