CuBr₂/TBHP‐Promoted Selective Dibromination and Bromohydroxylation of (Diphenylphosphoryl)allenes

Abstract

A cooperative CuBr2 and tert‐butyl hydroperoxide (TBHP) system allowed for the highly stereoselective dibromination and bromohydroxylation reactions of (diphenylphosphoryl)allenes under mild (room temperature) and operationally simple conditions. These reactions selectively proceeded through either a dibromination or bromohydroxylation process and are characterized by their broad substrate scope (22 examples), their step economy, and ability to be carried out on a gram scale. This method offers a useful protocol to access allyl bromides and alcohols. Moreover, synthetic applications of the dibromination products include a Suzuki–Miyaura cross‐coupling reaction and copper‐catalyzed cascade process, which could also afford various important derivatives.

Base‐Promoted Synthesis of β‐Ketophosphine Oxides from Diphenylphosphorylallenes

“…So far, chemists have developed various useful synthetic methodologies on the basis of allene chemistry,such as the hydroarylation of allenylic phosphonates, semihydrogenation of allenylic phosphonates and phosphine oxides, iodohydroxylation of allenylic phosphine oxides, and so on . Recently, our group have reported the methyltrioxorhenium‐catalyzed dihydroxylation, palladium‐catalyzed hydroarylation, and CuBr 2 /TBHP‐promoted bromohydroxylation of diphenylphosphorylallenes . On the basis of our continuing interest in the transformation of allene compounds, we further explored the hydration of diphenylphosphorylallenes to synthesize β ‐ketophosphine oxides (Scheme d).…”

Synthesis of 5-aminolevulinic acid with nontoxic regents and renewable methyl levulinate

“…These metal bromides were also found to be inactive in bromination as noted in previous studies. 22,23 The conventional bromination agent such as Br 2 , 2C 4 H 9 NOHBr$Br 2 and NBS can obviously improve the reaction ( Table 2, entry 14-17), although they were lower than that achieved with CuBr 2 (Table 2, entry 6). Experiments that screened for the bromine donors suggested that CuBr 2 was the most effective for the bromination of ML (Table 2, entry 6).…”