Table 2.

The condensation reaction of 1 with chlorooxoesters

No.	R2	R3	Procedurea	Time/h	Yield of 11–12/%	M.p. of 11–12/ °C
9	CH3	COOC2H5	A B C	38 1 1	4 42 82	104–105b
10	CH2COOC2H5	H	A B C	13 1 1	15 35 60	42–43

^aProcedure A: MeOH, MeONa, procedure B: EtOH, procedure C: step 1—MeOH, HC(OCH₃)₃, step 2—EtOH, H₂SO₄

^bRef. [15] 70–73 °C, Ref. [16] 109–110 °C