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Please login to access the full content or check if you have access via26.9.1.1.4.2 Variation 2: Transition-Metal-Catalyzed Substitution with Acid Halides
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Marsden, S. P., Science of Synthesis, (2005) 26, 1064.
Zerovalent palladium species insert readily into the C—Cl bond of acid chlorides to generate acylpalladium(II) chloride complexes. These usually undergo a rapid decarbonylation to give aryl-, vinyl-, or alkylpalladiums that undergo further reactions such as interception by alkenes in Heck processes. There are, however, two classes of reaction whereby the initially formed acylpalladium can be trapped by an alkene before decarbonylation takes place, allowing direct synthesis of α,β-unsaturated ketones (Scheme 22). The first example involves the use of bridgehead acid chlorides such as 90 to prepare enones, e.g. 91. In this case, the intermediate acylpalladium species are reluctant to undergo decarbonylation owing to strain in the potential products of the reaction.[86] Alternatively, aryl and hetaryl acid chlorides such as 92 react with alkyl vinyl ethers (e.g., 93) under palladium catalysis to generate vinylogous esters, e.g. 94.[87] The reactions are very highly regio- and stereoselective. Attempted extension to more substituted enol ethers or other alkene acceptors was unsuccessful, but the reaction tolerates a wide range of aromatic groups, provided there is no ortho substituent.
Meeeee 88 Meeeeeeee-Meeeeeeee Meeeeeeee ee Meeeeee[88,88]
Meeeeeeeeeee Meeeeeeee
(M)-8-Meeeeee[8.8.8]eeee-8-ee-8-eeeeeeeeee-8-ee-8-eee (88):[88]
M eeeeeee ee eeeeeee[8.8.8]eeeeeee-8-eeeeeeee eeeeeeee (88; 8.8 e, 88 eeee), eeeeeee (8.8 e, 88 eeee), Me(MMe)8 (88.8 ee, 8.8 eeee), eee Me8MMe (8.8 e, 88 eeee) eee eeeeee ee 888°M eee 8 e. Mee eeeeeee eee eeeeeee eeee 8 M MMe eee eeeeeeeee eeee Me8M (8 ×). Mee eeeeeeee eeeeeee eeeeee eeee eeeee (Me8MM8) eee eeeeeeeeeeee eeeee eeeeee. Mee eeeeeee eee eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee eee, eeeeee/Me8M 88:8) eeeeeeee ee eeeeeeeeeeeeeeeee (eeeeee); eeeee: 8.8 e (88%).
References
[86] | Meee, M.; Meee, M.; Meeeeeee, M.; Meeeeee, M., Meeeeeeeeee Meee., (8888) 88, 8888. |
[87] | Meeeeeeee, M.-M.; Meeeeeee, M., M. Mee. Meee., (8888) 88, 8888. |