Methodology for the Preparation of C1-Monoalkylated 1,2-Dihydro[C ₇₀] Derivatives: Formation of the "Other" Regioisomer

Deprotonation of 1,2-C₇₀H₂ with TBAOH, followed by alkylation with methyl bromoacetate, results in formation of a C1-monoalkylated 1,2-dihydro-C₇₀ derivative. The position of the alkyl group (C1) was established by NMR spectroscopy and comparison with literature spectra of C2-monoalkylated analogs. Presumably, C1-alkylation is the major process due to selective deprotonation of 1,2-C₇₀H₂ at C1. Substitution of benzyl bromide for methyl bromoacetate results in rapid dialkylation, unless the amount of base is carefully controlled, in which case C1-monobenzylation is the major process. This methodology for alkylation at C1 is complimentary to methods for the C2-monoalkylation of C₇₀ with Zn and methyl bromoacetate.