Rhodium(I) catalysis in olefin photoreactions
The photorearrangement (254 nm) of 1,5-cyclooctadiene (1) in the presence of rhodium(I) chloride to give 1,4-cyclooctadiene (4) was found by deuterium labeling to involve an intramolecular [1,3] shift of hydrogen. A rate- determining cleavage of an allylic C--H bond is indicated by a deuterium isotope effect, k/sub H//k/sub D/ = 1.55 +- 0.03 for the 1 $Yields$ 4 rearrangement. The acyclic 1,5-diene, 3,3-dimethyl-1,5-hexadiene (8), rearranges in the presence of rhodium(I) chloride upon uv irradiation (254 nm) to give cis-3,3-dimethyl-1,4- hexadiene (10) and the trans isomer 11 in a 1:4 ratio, respectively. This observation supports a mechanism for the photorearrangement of olefins catalyzed by rhodium(I) involving an initial photodissociation of one of two rhodium(I) coordinated carbon-carbon double bonds. This results in an increase in the coordinative unsaturation of rhodium(I) and enhances the proclivity of this d/sub s/ metal atom toward oxidative addition of an allylic C--H bond. A eta$sup 3$- allylrhodium hydride intermediate then gives rearranged olefin by reductive elimination. Lastly, a novel photochemical, rhodium(I) catalyzed hydrogen transfer is reported which gives cyclooctene (7) from cyclooctadienes under unprecedentedly mild conditions. (auth)
- Research Organization:
- Case Western Reserve Univ., Cleveland
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-33-002616
- OSTI ID:
- 4166597
- Journal Information:
- J. Am. Chem. Soc., v. 97, no. 21, pp. 6214-6221, Other Information: Orig. Receipt Date: 30-JUN-76
- Country of Publication:
- United States
- Language:
- English
Similar Records
Synthesis and subsequent rearrangement of chloro(pentafluorophenyl)-1,5-cyclooctadienepalladium(II), an illustrative example of endo attack to a coordinated double bond
Decomposition and hydrocarbon growth processes for hexadienes in nonpremixed flames