Synthetic Hypotensive Esters from Germine¹

Enantioselective Analysis of Methyl-Branched Alcohols and Acids in Rhubarb (Rheum rhabarbarum L.) Stalks

“…2-Methylbutanoic acid in Parmesan cheese, for example, exhibits an enantiomeric ratio of 75% (S):25% (R) (21). The only sources in which the (R)-acid has been shown to be predominant are medicinal plants, such as Veratrum species (e.g., Veratrum album and Veratrum Viride) (18,22,23).…”

Syntheses of isotopically labelled L-α-amino acids with an asymmetric centre at C-3

“…C 15 H 25 NO 3 S requires C, 60.20; H, 8.36; N, 4.68; S, 10.70%); ν max (CH 2 Cl 2 )/ cm Ϫ1 1688 (C᎐ ᎐ O); δ H (300 MHz) 0.95 and 1.15 (2 × 3H, 2 × s, 8-H 3 and 9-H 3 ), 1.34 [9H, s, C(CH 3 ) 3 ], 1.35 (2H, m), 1.89 (5H, m, 3-H 2 , 4-H, 5-H 2 and 6-H 2 ), 3.44 and 3.49 (each 1H, each d, D Ϫ116.1 (c 3.05 in CH 2 Cl 2 ) [lit., 44 Ϫ161.7 (c 3.20 in CH 2 Cl 2 )]; ν max (CHCl 3 )/cm Ϫ1 1694 (CO); δ H (300 MHz) 0.97 and 1.16 (2 × 3H, 2 × s, 8-H 3 and 9-H 3 ), 1.40 (2H, m), 1.90 (3H, m), 2.12 (2H, m, 3-H 2 , 4-H, 5-H 2 and 6-H 2 ), 2.40 (3H, s, COCH 3 ), 3.44 and 3.51 (2 × 1H, 2 × d, J 14.0, 10-H 2 ), 3.85 (1H, dd, J 7.7, 5.2, 2-H); δ C (75 MHz) 19.9 and 20.8 (C-8 and C-9), 23.2 (COCH 3 ), 26.4, 32.8 and 38.4 (C-3, C-5 and C-6), 44.7 (C-4), 47.8 and 48.4 (C-1 and C-7), 52.8 (C-10), 65.2 (C-2) and 168.6 (COCH 3 ); m/z (CI) 258.1159 (MH ϩ , 100%. C 12 H 20 NO 3 S requires 258.1164), 214(28), 135 (93), 109(24) and 83(36). The most polar fraction gave recovered auxiliary 39 (25.2 mg) as a white solid.The above reaction was repeated using sodium [1-13 C]acetate (2.498 g, 30.1 mmol) and (1S)-bornane-10,2-sultam 39 (7.127 g, 33.1 mmol).…”