PURPOSE: To obtain the subject compounds without using a thermally unstable ether adduct nor a dimethyl sulfide adduct generating malodor by reacting an olefin and an alkyl with a specific halogenated boron and diborane in a reactor.

CONSTITUTION: The compounds are expressed by R2R3BX (in a case that R and R1 are each an olefin, R2 and R3 are each an alkyl corresponding to R or R1; in a case that R and R1 are each an alkyl, R2 and R3 are each an alkenyl corresponding to R or R1) and are produced by reacting (A) a first reactant R selected from a group comprising an olefin and an alkyne with (B) a second reactant R1 selected from a group comprising an olefin and an alkyne, (C) diborane and (D) a boron trihalide of BX3 (X is fluoro, chloro, bromo, or iodo) in a single reactor under the condition that a molar ratio of the component D to the component C is (1/1.5)-(1.5/1). Preferably, at least one of the component A and the component B is an olefin expressed by the formula (R4 to R7 are each H, a 1-10C allyl, an alkyl or the like).