Enyne lactone formation

Ester-tethered enyne systems cycloisomerized to give lactone products (Eq. 11) [24]. Eor example, enyne 6 reacted under the Alder-ene conditions of [Rh(COD)Cl]2/BlNAP/ AgSbEg to give the corresponding lactone (Eq. 11). Once again free hydroxyl groups on the allylic terminus were incorporated into the cyclization precursors and subjected to the Alder-ene conditions, which led to the exclusive formation of the tautomerized products in good yields and enantioselectivities (Eq. 12). 

Formation of Dienes and Enynes by Coupling and Cross Coupling. The vinylation of methyl acrylate, methyl vinyl ketone, or acrolein with ( ) or (Z) vinylic halides under phase-transfer conditions gives high yields of (E,E) (eq 19) or E,Z) (eq 20) conjugated dienoates, dienones, and dienals, respectively. Coupling of vinyl halides or triflates with a,p or 8, /-unsaturated acids under phase-transfer conditions yields vinyl lactones. ... 

The Zhang s procedure based on the [Rh(cod)Cl]2/BINAP catalyst has been successfully extended to the Alder-ene cyclizations of enynes with amide [27] or ester functions [34] in the tethering chains. This efficient methodology allowed generation of a variety of functionalized lactames and y-lactones through highly stereoselective carbon-carbon bond formations (Fig. 10.20). 

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