Reaction Steps
Tertiary alcohol 17 (13.9 g, 72.4 mmol) is treated with NaCN according to general procedure B. TLC analysis (1:1 hexane/EtOAc) indicates that 17 is completely converted into a high Rf product within a few hours. Prolonged stirring of the reaction mixture first at rt(5 days), then at 50° C. (16 h), gives only a small amount of a lower Rf product. The reaction is worked up by the general method, and the mixture is purified by filtration through silica gel with 1:1 hexane/EtOAc. The material (8.0 g, 64%) proves to be (1H NMR) a ca. 1:1 mixture of olefin isomers formed by simple elimination of water from 17. Further elution of the silica gel with 10:1 CH2Cl2 /MeOH yields a small amount of the formamide (19, 1.8 g, 11%). The mixture of olefins is resubmitted to the general Ritter reaction conditions (but at rt for 5 days, then at 45-50° C. for 16 h) to give 5.5 g of 19 as a yellow oil after FC (10:1 CH2Cl2 /MeOH). The total yield of 19 from 17 is therefore 7.3 g(46%). The following NMR spectra are for a a. 75:25 mixture of amide rotamers. Signals for the major rotamer are designated A, and those for the minor rotamer re designated B. 1H NMR (CDCl3) 8.13(s,0.75,A), 7.80(d,0.25, J=12.3,B), 7.45-7.00(m,5 total), 6.02(br d,0.25,J=12.3,B), 5.25 (br s,0.75,A), 3.90-3.50(m,4 total), 3.08 (s,0.75, A), 2.85(s,0.25, B), 2.15-1.65 (m, 4 total); 13C NMR (CDCl3) 163.76 (B), 161.29 (A), 136.13 (A), 134.52 (B), 131.30 (B), 130.82 (A), 130.70 (B), 130.56 (A), 128.36 (A), 128.14 (B), 127.99 (A), 127.84 (B), 127.11 (B), 126.54 (A), 63.19 (A), 62.76 (B), 54.38 (A), 52.93 (B), 49.60 (B), 43.87 (A), 36.11 (B), 34.98 (A); MS(MW=219.3, EI,eE=70 eV) m/z 220 (M+H)+, 201, 174, 141, 128(base peak), 115, 100, 98, 91, 82, 70, 65, 53, 42.
