Alkoxycarbonylation intramolecular alkyne reactions

Palladium(ll)-catalyzed intramolecular stereoselective Irons alkoxycarbonylation of 4-alkyl- and 4-aryl-3-butyn-l-ols 7 gives /f-tetrasubstituted a-methylene-y-butyrolactones 8 if conducted in the presence of copper(II) chloride, methyloxirane and triethyl orthoacetate. In the absence of the copper salt, intramolecular dicarbonylation occurs (e.g., giving 9, see Section 1.5.8.3.3.). The latter reaction type is also observed if the alkyne moiety is substituted by a trimethylsilyl instead of an alkyl or aryl group60,61. 

Intramolecular acylation. When a carbonate ester containing an alkyne or allene unit" at the proper length is submitted to i-PrMgBr/( -PrO)4Ti, the multiple bond is metallated and becomes nucleophilic such that internal attack on the carbonyl group results in O —> C transfer of the alkoxycarbonyl group. Diethyl alkynyhnalonates also undergo a similar reaction. ... 

Trost et al. reported the first asymmetric total synthesis of pseudolaric acid B by exploiting a rhodium-catalyzed intramolecular [5-1-2] cycloaddition reaction of a vinylcyclopropane with an alkyne (Scheme 8.2) [4]. The vinylcyclopropane having a tethered alkyne moiety 12 was synthesized from chiral precursors 9 and 11. Treatment of 12 with a cationic rhodium(1) catalyst promoted the [5-1-2] cycloaddition reaction to form a [5.3.0]bicyclic skeleton of 13 in a diastereoselective fashion. A few steps of functional group transformations provided the alkoxycarbonyl... 

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