452914-50-0Relevant academic research and scientific papers
TiCl4-promoted Baylis-Hillman reactions of substituted 5-isoxazolecarboxaldehydes with cycloalkenones
Patra, Arundhati,Batra, Sanjay,Joshi, Bhawani S.,Roy, Raja,Kundu, Bijoy,Bhaduri, Amiya P.
, p. 5783 - 5788 (2002)
The Baylis-Hillman (BH) reaction of substituted 5-isoxazolecarboxaldehydes with cyclohexenone in the presence of TiCl4 invariably lead to the formation of hemiacetals beside the BH adducts. A similar reaction in the presence of DABCO, DBU, or 3-HQN yielded minor quantities of phenols in addition to the usual BH adducts. Similar to 5-isoxazolecarboxaldehydes, the TiCl4-mediated BH reaction of cyclohexenone with various benzaldehydes also furnishes hemiacetals in considerable yields. The reaction mechanism involving the formation of α-chloromethyl enone as an intermediate has been proposed. The synthesis of hemiacetals 5 and 14 from compound 4 in the presence of cyclohexenone and cyclopentenone, respectively, under acidic conditions indicates that enolization and aromatization of the cyclohexene ring are the key steps in the reaction mechanism.
