The synthetic equivalent of the given synthon is

Concept:

Synthetic Equivalent and Synthon:

• A reagent carrying out the function of a synthon, which cannot itself be used, often because it is too unstable.
• A reagent or generalized fragment, usually an ion produced by dissociation of a synthetic equivalent.

Explanation:

• t-butyl isocyanide is a type of alkyl isocyanide.
• Isocyanides can act as a nucleophile as well as electrophile through the same C atom.
• The adduct forms from the alkyl isocyanide at the alpha-C atom concludes the synthetic equivalent of the given synthon is t-butyl isocyanide.

Conclusion:

Hence, the synthetic equivalent of the given synthon is t-butyl isocyanide.