Selective Ruthenium-Catalyzed Transformations of Enynes with Diazoalkanes into Alkenylbicyclo[3.1.0]hexanes
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- 作者：Florian Monnier ; Chloé ; Vovard-Le Bray ; Dante Castillo ; Vincent Aubert ; Sylvie Dé ; rien ; Pierre H. Dixneuf ; Loic Toupet ; Andrea Ienco ; Carlo Mealli
- 刊名：Journal of the American Chemical Society
- 出版年：2007
- 出版时间：May 9, 2007
- 年：2007
- 卷：129
- 期：18
- 页码：6037 - 6049
- 全文大小：358K
- 年卷期：v.129,no.18(May 9, 2007)
- ISSN：1520-5126
文摘
Reaction of a variety of C
CH bond-containing 1,6-enynes with N2CHSiMe3 in the presence ofRuCl(COD)Cp* as catalyst precursor leads, at room temperature, to the general formation of alkenylbicyclo[3.1.0]hexanes with high Z-stereoselectivity of the alkenyl group and cis arrangement of the alkenyl groupand an initial double-bond substituent, for an E-configuration of this double bond. The stereochemistry isestablished by determining the X-ray structures of three bicyclic products. The same reaction with 1,6-enynes bearing an R substituent on the C1 carbon of the triple bond results in either cyclopropanation ofthe double bond with bulky R groups (SiMe3, Ph) or formation of alkylidene-alkenyl five-memberedheterocycles, resulting from a 
elimination process, with less bulky R groups (R = Me, CH2CH=CH2).The reaction can be applied to in situ desilylation in methanol and direct formation of vinylbicyclo[3.1.0]hexanes and to the formation of some alkenylbicyclo[4.1.0]heptanes from 1,7-enynes. The catalytic formationof alkenylbicyclo[3.1.0]hexanes also takes place with enynes and N2CHCO2Et or N2CHPh. The reactioncan be understood to proceed by an initial [2+2] addition of the Ru=CHSiMe3 bond with the enyne CCHbond, successively leading to an alkenylruthenium-carbene and a key alkenyl bicyclic ruthenacyclobutane,which promotes the cyclopropanation, rather than metathesis, into bicyclo[3.1.0]hexanes. Density functionaltheory calculations performed starting from the model system Ru(HCCH)(CH2=CH2)Cl(C5H5) show thatthe transformation into a ruthenacyclobutane intermediate occurs with a temporary 
3-coordination of thecyclopentadienyl ligand. This step is followed by coordination of the alkenyl group, which leads to a mixedalkyl-allyl ligand. Because of the non-equivalence of the terminal allylic carbon atoms, their coupling favorscyclopropanation rather than the expected metathesis process. A direct comparison of the energy profileswith respect to those involving the Grubbs catalyst is presented, showing that cyclopropanation is favoredwith respect to enyne metathesis.
CH bond-containing 1,6-enynes with N2CHSiMe3 in the presence ofRuCl(COD)Cp* as catalyst precursor leads, at room temperature, to the general formation of alkenylbicyclo[3.1.0]hexanes with high Z-stereoselectivity of the alkenyl group and cis arrangement of the alkenyl groupand an initial double-bond substituent, for an E-configuration of this double bond. The stereochemistry isestablished by determining the X-ray structures of three bicyclic products. The same reaction with 1,6-enynes bearing an R substituent on the C1 carbon of the triple bond results in either cyclopropanation ofthe double bond with bulky R groups (SiMe3, Ph) or formation of alkylidene-alkenyl five-memberedheterocycles, resulting from a elimination process, with less bulky R groups (R = Me, CH2CH=CH2).The reaction can be applied to in situ desilylation in methanol and direct formation of vinylbicyclo[3.1.0]hexanes and to the formation of some alkenylbicyclo[4.1.0]heptanes from 1,7-enynes. The catalytic formationof alkenylbicyclo[3.1.0]hexanes also takes place with enynes and N2CHCO2Et or N2CHPh. The reactioncan be understood to proceed by an initial [2+2] addition of the Ru=CHSiMe3 bond with the enyne CCHbond, successively leading to an alkenylruthenium-carbene and a key alkenyl bicyclic ruthenacyclobutane,which promotes the cyclopropanation, rather than metathesis, into bicyclo[3.1.0]hexanes. Density functionaltheory calculations performed starting from the model system Ru(HCCH)(CH2=CH2)Cl(C5H5) show thatthe transformation into a ruthenacyclobutane intermediate occurs with a temporary 3-coordination of thecyclopentadienyl ligand. This step is followed by coordination of the alkenyl group, which leads to a mixedalkyl-allyl ligand. Because of the non-equivalence of the terminal allylic carbon atoms, their coupling favorscyclopropanation rather than the expected metathesis process. A direct comparison of the energy profileswith respect to those involving the Grubbs catalyst is presented, showing that cyclopropanation is favoredwith respect to enyne metathesis.