Cesium carbonate → Ethyl 3-(4-chlorophenyl)propiolate

Participants

Reaction Conditions

Reaction Steps

Under argon atmosphere, a four neck flask was charged with 1-chloro-4-iodo-benzene (130.0 g, 0.55 mol), bis(triphenylphosphine) palladium(II) chloride (7.57 g, 10.8 mmol, 2 mol %), copper(I) iodide (4.19 g, 22.0 mmol, 4 mol %) and dry THF (1.4 l). At r.t., cesium carbonate (355.3 g, 1.09 mol, 2 eq.) was added over 5 min. Afterwards propynoic acid ethyl ester (111.3 ml, 1.09 mol, 2 eq.) was added, and the reaction mixture was stirred overnight at 35° C. An additional portion of propynoic acid ethyl ester (11.1 ml, 0.11 mol, 0.2 eq.) was added, and the reaction was stirred for another 3 h at 35° C. The reaction mixture was evaporated to dryness, and the residue was taken up in toluene (0.5 l) and heptane (1 l). The resulting suspension was stirred at 40° C. for 1 h and filtered over celite. The filtrate was concentrated, and the product purified by silica gel filtration (toluene/heptane 1:2) to yield 72.6 g (61%) of Va as a light yellow solid.

Provenance & Evidence