After cooling, the solution was continuously extracted with ether for 18 h. The ether was removed at reduced pressure, leaving a yellow oil, which crystallized on standing and proved to be the title acid (111 g, 97%), which was characterized by conversion to its ethyl ester, whc se physical properties were in accord with literature data: 15'H NMR (CC14) 6 4.17 (2 H, q, J= 7 Hz), 3.27 (5 H, m), 1.27 (3 H, t, J= 7 Hz); 13C NMR (CC14) 201.48 (C3),
