Direct Carbon−Carbon Bond Formation via Reductive Soft Enolization: A Kinetically Controlled syn-Aldol Addition of α-Halo Thioesters and Enolizable Aldehydes
摘要:
The direct addition of enolizable aldehydes and alpha-halo thioesters to produce beta-hydroxy thioesters enabled by reductive soft enolization is reported. The transformation is operationally simple and efficient and has the unusual feature of giving high syn-selectivity, which is the opposite of that produced for (thio)esters under conventional conditions. Moreover, excellent diastereoselectivity results when a chiral nonracemic alpha-hydroxy aldehyde derivative is used.
Boronic Acid Mediated Carbocyanation of Olefins and Vinylation of Alkyl Iodides
作者:Reina Hara、Chahinaz Khiar、Nitin S. Dange、Pierre Bouillac、Frédéric Robert、Yannick Landais
DOI:10.1002/ejoc.201800444
日期:2018.8.15
The tin‐free carbocyanation of olefins and the addition of alkyliodides to vinylsulfones were developed by using phenylboronic acid as an aryl radical precursor and tin surrogate. The resulting aryl radical then selectively abstracted an iodineatom from the alkyliodide to generate a radical that was employed in C–C bond forming processes.
The free‐radical three‐component carbocyanation of electron‐rich olefins was investigated with p‐tosyl cyanide as cyanide source. The scope and limitations of the process were established by varying the nature of the alkene and radical precursor. Carbocyanation of chiral allylsilanes was shown to occur with high diastereocontrol, leading to syn β‐silyl nitriles. The origin of the stereocontrol was
Free-Radical Carbocyanation of Cyclopropenes: Stereocontrolled Access to All-Carbon Quaternary Stereocenters in Acyclic Systems
作者:Nitin S. Dange、Frédéric Robert、Yannick Landais
DOI:10.1021/acs.orglett.6b03163
日期:2016.12.2
Free-radical carbocyanation of cyclopropenes offers straightforward access to tetrasubstituted cyclopropanes in satisfying yields with moderate diastereoselectivity. The incorporation of various functional groups on the cyclopropane ring allows a subsequent base-mediated ring-opening reaction leading to functionalized acyclic systems having an all-carbon quaternary stereocenter.
The first total synthesis of eucophylline was reported in 10 steps and 10% overall yield. The naphthyridine core of eucophylline was prepared through the coupling between a strained azabicyclo[3.3.1]nonan-2-one and a trisubstituted benzonitrile, followed by a cyclization of the corresponding amidine. This coupling reaction was shown to proceed through a stable bicyclic chloroenamine intermediate. The