Dimethyl sulfide–boron trihalide-mediated reactions of α, β-unsaturated ketones with aldehydes: one-pot synthesis of Baylis–Hillman adducts and α-halomethyl …
The reactions of aldehydes with 3-buten-2-one (2) were conducted in the presence of BBr3· Me2S or BCl3· Me2S and then worked up with aqueous NaHCO3, affording the α-methylene aldol 3, α-halomethyl aldol 4 or 6, and α-halomethyl enones 5 or 7, respectively. In contrast, the reactions quenched with water gave the α-halomethyl enones 5 or 7 in high yields, while the work-up with an aqueous 10% trimethylamine gave the α-methylene aldol 3. The ...