= Solution
\b[The favoured insertion leaves <nickel> attached to the methyl-substituted <alkyne> <carbon>; the aryl group bonds to the SiMe$_3$-substituted <carbon>.] This is the connectivity leading to the illustrated ring-closed product: the <carbon> carrying methyl subsequently attacks the ester carbonyl.
The bulky trimethylsilyl substituent is kept away from the crowded phosphine-ligated <nickel> centre in the insertion arrangement. The alternative orientation would place Ni next to the more demanding SiMe$_3$ end. <regioselectivity> can also reflect electronic polarization of a silyl-substituted <alkyne> and stabilization of the resulting alkenyl complex. The ortho ester helps capture the insertion product by <oxygen> coordination and subsequent ring closure. \b[Steric discrimination at insertion, reinforced by the accessible intramolecular cyclization, accounts for the observed direction]; the product drawing alone is not a quantitative separation of steric and electronic contributions.
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