# Mechanism for Nagata Alkylation

I am looking into the mechanism for the Nagata Alkylation; however, I cannot find anything more specific than the mechanism listed below.

I am only refering to the formation of the first intermediate, not the cyclization of the ortho-quinone methide. I would assume that the phenylboronic acid first forms an ester with the phenol and then the lewis-basic carbonyl attacks the boron. This might then make an electrophillic carbon that can undergo an alkylation reaction. I am not very sure about this proposal of mine, and I was wanting to ask if anyone had any suggestions as to how this mechanism might be occuring.

This reaction of ortho-alkylation of phenols was first indroduced by Nagata and coworkers in 1979 (Ref.1). Accordingly, for example, reaction of a phenol with a large excess of an aldehyde and a slight excess of benzeneboronic acid in refluxing benzene (or toluene) in the presence of $$\pu{0.1 mol}$$ equivalent of propanoic acid (or trichloroacetic acid) gave about 97% of the expected product, a 2-phenyl-4 H-1,3,2-benzodioxaborin, as a crystalline product (Ref.1):
1. Wataru Nagata, Kyo Okada, Tsutomu Aoki, “ortho-Specific $$\alpha$$-Hydroxyalkylation of Phenols with Aldehydes. An Efficient Synthesis of Saligenol Derivatives,” Synthesis 1979, (5), 365-368 (DOI: 10.1055/s-1979-28683).