Ketones formation from alkenyl halides

Ketone formation from aryl and alkenyl halides via carbonylation and addition to alkenes is accomplished hy heating the substrates with Mo(CO)6 in DMF at 160°." ... 

Formation of lactones from alkenyl halides has also been reported as part of natural product syntheses, as in Marshall s approach to ( )-aristolactone,t or as a means to support stereochemical assignments. " So far, the reactions discussed have all involved attack of a free hydroxyl group on the acylpalladium species. A closely related approach involves attack of an 0-enolate, which is usually generated from the corresponding ketone. The concept is shown in Scheme 11. 

No intennolecular reaction of malonate or /3-keto esters with halides has been reported, but the intramolecular reaction of /3-diketones such as 790 and malonates proceeds smoothly[652,653]. Even the simple ketone 791 can be arylated or alkenylated intramolecularly. In this reaction, slow addition of a base is important to prevent alkyne formation from the vinyl iodide by elim-ination[654]. 

The use of vinyl inflates in place of halides is attractive due to their easy formation from ketones and the readiness with which they undergo Pd-catalyzed chemistry. A method for the carbonylation of hydroxy alkenyl triflates using Pd(PPh3)4 as catalyst was developed by Crisp and Meyent ii A variety of fused butenolides were synthesized in good to excellent yields using this protocol, as shown in Scheme 9. 

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