wu hua 2011 4 23
Download
Skip this Video
Download Presentation
Wu Hua 2011-4-23

Loading in 2 Seconds...

play fullscreen
1 / 34

Wu Hua 2011-4-23 - PowerPoint PPT Presentation


  • 132 Views
  • Uploaded on

Rhodium Catalyzed Alkene and Alkyne Hydroacylation. Wu Hua 2011-4-23. Content. Intramolecular Alkene Hydroacylation. Intermolecular Alkene Hydroacylation. Intramolecular Alkyne Hydroacylation. Intermolecular Alkyne Hydroacylation. First reported:.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Wu Hua 2011-4-23' - imogene


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
wu hua 2011 4 23

Rhodium Catalyzed Alkene and

Alkyne Hydroacylation

Wu Hua

2011-4-23

slide2

Content

Intramolecular Alkene Hydroacylation

Intermolecular Alkene Hydroacylation

Intramolecular Alkyne Hydroacylation

Intermolecular Alkyne Hydroacylation

slide3

First reported:

The reaction was discovered by K. Sakai in 1972 as part in a synthetic route to certain prostanoids

Proposed mechanism:

Sakai, K.; Ide, J.; Oda, O.; Nakamura, N. Tetrahedron Lett. 1972,1287.

slide4

Milstein, D. J. Chem. Soc., Chem. Commun. 1982, 1357.

Lochow, C. F.; Miller, R. G. J. Am. Chem. Soc. 1976, 98, 1281.

Larock, R. C.; Oertle, K.; Potter, G. F. J. Am. Chem. Soc. 1980, 102, 190.

slide5

Pluth, J. J. J. Am. Chem.Soc. 1977, 99, 8055.

Inactive [Rh(diphos)(CO)2]+.

Inactive [Rh(diphos)(CHCN)2]+.

Fairlie, D. P.; Bosnich, B. Organometallics 1988, 7, 936.

slide7

Larger Ring Systems

a. Ring closure of these larger rings is generally slower than for five-ring formation

b. Decarbonylation can become problematic.

c. If a five-membered closure is possible, then this pathway will usually be followed.

slide8

The authors reasoned that cyclopentanone formation is disfavored due to the ring strain that would be present in the resulting 5,5,5-tricyclic product.

Gable, K.; Benz, G. A. Tetrahedron Lett. 1991, 32, 3473.

slide9

Sato, Y.; Oonishi, T.; Mori, M. Angew. Chem., Int. Ed. 2002, 41, 1218.

Oonishi, Y.; Mori, M.; Sato, Y. Synthesis 2007, 2323.

slide11

The experiments led to two D-containing products in a ratio that exactly matched the E/Z ratio of the

substrates. The authors proposed that the E isomer generated the expected cyclooctenone directly, via the mechanism. However, to account for the unexpected scrambling of the D-label, they proposed

isomerization of the Z alkene via five-membered rhodacycles leading to intermediate, featuring an E-configured alkene.

slide12

Stereoselective Reactions

Sakai, K. Tetrahedron Lett. 1984, 25, 961.

slide13

Enantioselective Systems

James, B. R.; Young, C. G. J. Chem. Soc., Chem. Commun. 1983, 1215.

Sakai, K. Tetrahedron Lett. 1989, 30, 6349.

slide15

Intermolecular Alkene Hydroacylation

Their success was attributed to intramolecular coordination of the alkene to aid in catalyst stabilization. The use of heteroatom chelation has emerged as a successful strategy for intermolecular hydroacylation and a number of systems have been reported.

Miller, R. G. J. Organomet. Chem. 1980, 192, 257.

slide16

Suggs first isolated acyl rhodium(III) complexfrom the reaction of quinoline-8-carboxaldehyde and Wilkinson’s complex, and found that after treatment with AgBF4 and octene, the hydroacylation adduct could be isolated.

Suggs, J. W. J. Am. Chem. Soc. 1978, 100, 640.

slide17

Lee, H.; Jun, C.-H. Bull. Korean Chem. Soc. 1995, 16, 66.

Suggs, J. W. J. Am. Chem. Soc. 1979, 101, 489.

slide20

The rhodium complex first catalyzes the oxidation of the alcohol to the aldehyde, using an equivalent of alkene as the oxidant, before promoting the hydroacylation reaction as described previously.

Jun, C.-H.; Na, S.-J. Angew. Chem., Int. Ed. 1998, 37, 145.

slide22

Salicylaldehydes in combination with diene substrates

Suemune, H. Org. Lett. 2003, 5, 1365.

slide26

Intramolecular Alkyne Hydroacylation

Perhaps due to the desire to generate organic molecules containing stereogenic centers, the study of alkynes in hydroacylation reactions has received significantly less attention than the alkene-based process.

In order to achieve the 4-alkynal to cyclopentenone

conversion, the hydroacylation mechanism must involve an unusual trans addition of the rhodium hydride across the alkyne.

An impressive range of substituents could be tolerated, including pendent alkene and alkyne functionalities. The choice of catalyst and solvent was found to be crucial to the success of these reactions.

Tanaka, K.; Fu, G. C. J. Am. Chem. Soc. 2001, 123, 11492.

slide28

Because no sp3 centers are generated in these reactions, the group has investigated kinetic resolution and desymmetrization procedures.

Tanaka, K.; Fu, G. C. J. Am. Chem. Soc. 2002, 124, 10296.

slide30

Kokobu, K.; Matsumasa, K.; Miura, M.; Nomura, M. J. Org. Chem. 1997, 62, 4564.

Willis, M. C.; McNally, S. J.; Beswick, P. J. Angew. Chem., Int. Ed. 2004, 43, 340.

slide34

Tanaka, Ken (8)

Dong, Vy M. (6)

Brookhart, Maurice (5)

Jun, Chul-Ho (5)

Krische, Michael J. (5)

Lenges, Christian P. (5)

Tanaka, Ken (8)

Dong, Vy M. (6)

Brookhart, Maurice (5)

Jun, Chul-Ho (5)

Krische, Michael J. (5)

Lenges, Christian P. (5)

Summary

Tanaka, Ken

Dong, Vy M

Brookhart, Maurice

Jun, Chul-Ho

Krische, Michael J

Lenges, Christian

Glorius, Frank

However, limitations still remain to the transformations that can be achieved; intramolecular reactions to generate rings other than five-membered systems are not

trivial, and the development of an intermolecular process with wide substrate scope has still not been achieved. The development of regio- and enantio-control in intermolecular

reactions is also in its infancy.

ad