A versatile method for the preparation of allenic alcohols
作者:Gary E. Keck、R.R. Webb
DOI:10.1016/s0040-4039(00)87530-9
日期:1982.1
A convenient three step procedure to a variety of allenicalcohols is described, which relies on a highly unusual partitioning between two reaction pathways depending on the mode of addition of a reagent.
A series of nitrogen-tethered allenynes (‘5-aza-1,2-dien-7-ynes’) 1 were transformed to the corresponding 3-acyl-4-alkenylpyrrolidines 3 when treated with a catalytic amount of PtCl2 in MeOH at 70°. Initial Pt-promoted cyclization forms a nonclassical carbocationic intermediate. In contrast to the cycloisomerization in toluene, which produced the bicyclic cyclobutenes 2, the intermediate is intercepted
The enantioselective Claisenrearrangement of allenyl vinyl ethers was realized to access branched 1,3-dienyl-substituted all-carbon quaternary stereocenters using a NiII-N,N[prime or minute]-dioxide complex.
实现了烯基乙烯基醚的对映选择性克莱森重排,以使用Ni II - N,N [伯或分钟]-二氧化物络合物接近支链的1,3-二烯基取代的全碳季立体中心。
Nickel-Catalyzed Chemo- and Enantioselective Coupling between Cyclobutanones and Allenes: Rapid Synthesis of [3.2.2] Bicycles
作者:Xuan Zhou、Guangbin Dong
DOI:10.1002/anie.201609489
日期:2016.11.21
Herein an intramolecular nickel‐catalyzed (4+2) coupling between cyclobutanones and allenes, by C−C cleavage, is reported. The reaction provides a distinct approach for accessing [3.2.2] bicyclic scaffolds which are challenging to prepare through conventional approaches. The reaction is efficient, chemoselective, and pH/redox neutral. Room temperature conditions and low catalyst loadings can be adopted