[83816-41-5] C₃H₅BO₂ (MW 83.88)

InChI = 1S/C3H5BO2/c1-2-3-4(5)6/h3,5-6H,1H2

InChIKey = UWYKUBJFERKTAF-UHFFFAOYSA-N

(propargylating reagent for carbonyl groups; chiral allenylboronic ester as a reagent for enantioselective alkylation;¹ 1,3-asymmetric induction in propargylation of β-hydroxy ketones²)

Physical Data: mp 150 °C (dec).

Solubility: sol ether, alcohol.

Form Supplied in: white solid; widely available.

Analysis of Reagent Purity: ¹H NMR (CDCl₃–Me₂SO-d₆) δ 4.48 (d, J = 5.8 Hz, 1H), 4.51 (d, J = 7.2 Hz, 1H), 4.83 (dd, J = 5.8 and 7.2 Hz, 1H), 6.52 (br s, 2H).

Preparative Method: from Propargylmagnesium Bromide and Trimethyl Borate.¹

Handling, Storage, and Precautions: allenylboronic acid can be stored at −20 °C under argon. In air, it catches fire within several minutes. It should only be used in a fume hood.