R. Hekmatshoar et al., Reductive coupling of carbonyl compounds to pinacols with zinc in THF-saturated aqueous ammonium chloride, MONATS CHEM, 132(6), 2001, pp. 689-691
In the presence of metallic zinc, aldehydes and ketones experience reductiv
e coupling in tetrahydrofuran-saturated aqueous ammonium chloride (5:3) to
afford the corresponding pinacols in moderate to high yields.