# Synthesis of Alkenylgold(I) Complexes Relevant to Catalytic Carboxylative Cyclization of Unsaturated Amines and Alcohols

## TL;DR

This paper describes a new method to synthesize alkenylgold(I) complexes from unsaturated amines and alcohols using carboxylation under mild conditions.

## Contribution

A novel catalytic system for carboxylative cyclization of unsaturated amines and alcohols using a hydroxidogold(I) complex is introduced.

## Key findings

- Alkenylgold(I) complexes with cyclic urethane or carbonate frameworks were formed in high yields under mild conditions.
- Protonation of the alkenyl complexes yielded five- or six-membered carboxylation products.
- Decarboxylation occurred for complexes derived from allenylmethyl alcohol, recovering the starting material.

## Abstract

The carboxylation of unsaturated amine and alcohol compounds, including 4-benzylamino-1-phenyl-1-butyne (homopropargylamine), 2-butyne-1-ol (propargylic alcohol), and 2,3-butadiene-1-ol (allenylmethyl alcohol), using the hydroxidogold(I) complex, AuOH(IPr) [IPr = 1,3-bis(2,6-diisopropylphenyl)-imidazol-2-ylidene], produces corresponding alkenylgold(I) complexes with a cyclic urethane or carbonate framework in high yields. The reaction takes place in aprotic THF at room temperature under the atmospheric pressure of CO2 in the absence of base additives. The products were characterized by NMR spectroscopy, elemental analysis, and X-ray crystallography. The functionalized alkenyl complexes prepared from the alkynes can be protonated by treatment with an equimolar amount of acetic acid to afford five- or six-membered carboxylation products, whereas the related alkenyl complex derived from allenylmethyl alcohol decomposed to recover the starting allene via ring-opening decarboxylation.