“…ClsH2203 requires M, 250.157); v,,,(KBr)/cm-' 3480, 1746 and 1665; 6,6. 13 (1 H, d, J 1.2), 5.59 (1 H,brd,J1.2),4.47(1H,ddd,J1.7,5.0and5.0),2.98(1H,m), 2.06 (1 H, dd, J 1.5 and 15.5), 1.35-1.94 (9 H, m), 1.21 (3 H, s), 1.13 (3 H, s) and 1.08 (1 H, dd, J2.5 and 13.0); 6, 170.6, 142.2, 120.0, 77.0, 71.2, 48.8, 44.4, 42.0, 41.5, 41.1, 32.5, 30.4, 24.9, 20.0 and 17.3; m/z 250 ( M + , 17%), 232 (42), 163 (71), 147 (25), 133 (28), 121 (47), 11 1 (35), 99 (51), 91 (76), 86 (58), 71 (76), 67 (58) and 53 (100).…”