Rings of five and six: Donor alkenyl rhodiumcarbenoidsgeneratedfrom 3,3‐dimethylcyclopropenylcarbinols exhibit high reactivity in intramolecular CHinsertions. The reactions proceed under remarkably mild conditions, tolerate the presence of the free hydroxy group, and afford an efficient and stereoselective access to a variety of functionalized carbocycles and oxygen heterocycles.
Cyclopropenylcarbinol Derivatives as New Versatile Intermediates in Organic Synthesis: Application to the Formation of Enantiomerically Pure Alkylidenecyclopropane Derivatives
作者:Samah Simaan、Ahmad Masarwa、Elinor Zohar、Amnon Stanger、Philippe Bertus、Ilan Marek
DOI:10.1002/chem.200901074
日期:2009.8.24
The copper‐catalyzed carbomagnesiation (or hydrometalation) reaction of chiralcyclopropenylcarbinolderivatives, obtained by means of a kinetic resolution of secondary allylic alcohols, leads to an easy and straightforward preparation of enantiomericallypurealkylidenecyclopropanederivatives. The reaction mechanism is composed of a syn‐carbometalation followed by a syn‐elimination reaction. To gain
Alloc=allyloxycarbonyl, Boc=tert‐butyloxycarbonyl). These reactions are the first examples of the formation of medium‐sized rings by the intramolecular cyclopropanation of an alkene with a donor‐substituted rhodium carbenoid, which is not generated from a diazo compound.
Synthesis of Bifunctional Allylic Compounds by Using Cyclopropenes as Functionalized Allyl Equivalents
作者:Sergio Mata、Luis A. López、Rubén Vicente
DOI:10.1002/anie.201806961
日期:2018.8.27
The synthesis of uncommon bifunctional allylic derivatives bearing a silane and an alcohol within the same allylic framework is reported. This method relies on the coupling of hydrosilanes with substituted and functionalized cyclopropenes, which deliver the allyl fragment. Rhodium(II) catalysts provide regioselective access to vinyl carbene intermediates, which easily undergo Si−H bond insertions.
Regioselective Carbon–Carbon Bond Cleavage in the Oxidation of Cyclopropenylcarbinols
作者:Ahmad Basheer、Masaaki Mishima、Ilan Marek
DOI:10.1021/ol201581c
日期:2011.8.5
The strained double bond of cyclopropenylcarbinols undergoes a facile oxidation reaction to lead to unsaturated carbonyl derivatives. The distribution of the formed products depends on the relative stability of carbon-centered radical species, and the Sharpless kinetic resolution leads to enantiomerically pure Baylis–Hillman enal adducts.