N-Heterocyclic Carbene (NHC)-Rhodium-Catalyzed Carbonylative CC Bond Formation of Allenols with Arylboronic Acids under Carbon Monoxide
作者:Soo Young Choi、Young Keun Chung
DOI:10.1002/adsc.201100309
日期:2011.10
(3-Butyl-1-methylimidazole)(1,5-cyclooctadiene)rhodium chloride [Rh(Ibm)(cod)Cl] was found to be an efficient catalyst in the carbonylative arylation of allenols with arylboronicacids in the presence of carbonmonoxide. Efficient, simple, and versatile methods for the synthesis of 2-methylene-1-arylbut-3-en-1-ones have thus been developed.
Rhodium Complex-Catalyzed Cycloisomerization of Allenenes: Exo and Endo Cyclization Depending on the Auxiliary Ligands
作者:Tatsuya Makino、Kenji Itoh
DOI:10.1021/jo035551x
日期:2004.1.1
having an exo-alkylidene moiety. In this cycloisomerization, (E)- and (Z)-allenenes are transformed stereospecifically to the corresponding cyclic (E)- and (Z)-1,4-dienes, respectively. On the other hand, the reactions under carbon monoxide atmosphere exclusively afford seven-membered-ring products through an endo-mode cyclization. The unusual cyclization involves an allylic C−H activation process. The
Highly Regio- and Stereoselective Synthesis of Alkylidenecyclopropanes via Ru(II)-Pheox Catalyzed Asymmetric Inter- and Intramolecular Cyclopropanation of Allenes
An efficient protocol for the synthesis of optically active alkylidenecyclopropanes (ACPs) via the Ru(II)-Pheox catalyzed asymmetric cyclopropanation of allenes has been established. This catalytic system proceeded with high regioselectivity to give the ACP products in high yield with high diastereoselectivity (up to 99/1) and enantioselectivity (up to 99% ee).
Dynamic Kinetic Asymmetric Allylic Alkylations of Allenes
作者:Barry M. Trost、Daniel R. Fandrick、Diana C. Dinh
DOI:10.1021/ja0543705
日期:2005.10.1
The dynamic kineticasymmetricallylicalkylations of racemic allene acetates has been developed with the DACH−phenyl Trost ligand 2 to give general access to allenes with high enantiomeric excess (84−95%) for both malonate and amine nucleophiles. Further, a most unusual dependence of enantioselectivity on base has been uncovered. The magnitude of the enantioselectivity is heavily dependent on the
C sp 3H Bond Activation Triggered by Formation of Metallacycles: Rhodium(I)-Catalyzed Cyclopropanation/Cyclization of Allenynes
作者:Yoshihiro Oonishi、Yoshitaka Kitano、Yoshihiro Sato
DOI:10.1002/anie.201203772
日期:2012.7.16
Giving direction: An CHbondactivation directed by a rhodacycle intermediate has been found to occur in a RhI‐catalyzed reaction between an allene moiety having a tert‐butyl substituent, and tethered alkynes. Cyclic compounds containing a cyclopropane ring were obtained in good to high yields (up to 92%).