Catalytic C−C Coupling via Transfer Hydrogenation: Reverse Prenylation, Crotylation, and Allylation from the Alcohol or Aldehyde Oxidation Level
作者:John F. Bower、Eduardas Skucas、Ryan L. Patman、Michael J. Krische
DOI:10.1021/ja077389b
日期:2007.12.1
reductant, aldehydes 1b−6b are converted to the very same adducts 1c−6c, 1d−3d, and 1e. Isotopic labeling studies corroborate a mechanism involving hydrogen donation from the reactant alcohol or sacrificial alcohol (i-PrOH). The ability to achieve carbonyl addition directly from the alcohol oxidation level circumvents the redox manipulations so often required to convert alcohols to aldehydes. Further
作者:Jonathan Z. Shezaf、Catherine G. Santana、Connor Saludares、Edward S. Briceno、Ken Sakata、Michael J. Krische
DOI:10.1021/jacs.3c06734
日期:2023.8.23
correlation between metal-centered stereogenicity and regioselectivity in a catalytic process is described. Alternate pseudo-diastereomeric chiral-at-ruthenium complexes of the type RuX(CO)[η3-prenyl][(S)-SEGPHOS] form in a halide-dependent manner and display divergent regioselectivity in catalytic C–C couplings of isoprene to alcohol proelectrophiles viahydrogen autotransfer. Whereas the chloride-bound ruthenium-SEGPHOS
描述了催化过程中金属中心立体异构性和区域选择性之间的第一个相关性。 RuX(CO)[η 3 -prenyl][( S )-SEGPHOS] 类型的替代假非对映手性钌络合物以卤化物依赖性方式形成,并在异戊二烯与异戊二烯的催化 C-C 偶联中表现出不同的区域选择性。醇亲电体通过氢自转移。氯化物结合的钌-SEGPHOS络合物更倾向于卤化物和羰基配体之间的反式关系,并提供羰基仲异戊二烯化的产物,而碘化物结合的钌-SEGPHOS络合物更倾向于卤化物和羰基配体之间的顺式关系,并提供羰基仲异戊二烯化的产物。羰基叔异戊二烯化的产物。通过31 P NMR 和 X 射线衍射对溶液和固相中的氯化物和碘化物结合的钌-SEGPHOS 配合物进行了表征。碘化物结合催化剂的密度泛函理论计算暗示了科廷-哈米特型场景,其中仲异戊二烯和叔异戊二烯钌配合物的平衡混合物中醛配位的过渡态是速率和产物决定的。因此,对以金属为中心的非
Anti-Markovnikov Hydrofunctionalization of Alkenes: Use of a Benzyl Group as a Traceless Redox-Active Hydrogen Donor
A protocol for the anti-Markovnikov hydrofunctionalization of alkenes has been developed by the use of a benzylgroup as a traceless redox-active hydrogen donor. Under copper catalysis and in the presence of CF3- or N3-containing hypervalent iodine reagents, a series of homoallylic alcohol derivatives were hydrofunctionalized regioselectivity. A similar principle was also applied to the hydrofunctionalization
Carbonyl Allylation in the Absence of Preformed Allyl Metal Reagents: Reverse Prenylation via Iridium-Catalyzed Hydrogenative Coupling of Dimethylallene
作者:Eduardas Skucas、John F. Bower、Michael J. Krische
DOI:10.1021/ja075971u
日期:2007.10.1
Iridium-catalyzed hydrogenation of dimethylallene in the presence of aromatic, heteroaromatic, and aliphatic carbonyl electrophiles 1a-12a delivers products of reverse prenylation 1b-12b. Reductive coupling of dimethyl allene to aldehyde 8a under an atmosphere of deuterium provides deuterio -8b. As revealed by H-2 NMR analysis, deuterium incorporation is observed at the vinylic position (80% H-2). Unlike established methods for carbonyl allylation, the present protocol circumvents the use of stoichiometrically preformed organometallic reagents.