A new non-head-to-tail monoterpene from Artemesia tridentata. (2, 3)-1,2-epoxy-2,5-dimethyl-3-vinyl-4-hexene. (Oxido santolina triene).

Some aromatic compounds from the marine sponge Plakortis halichondrioides

“…7, 7 Hz), 2.67 (dt, 1 H,J= 11, 9, 9 Hz), 4.16 (dq, 1 H, J = 9, 6, 6, 6 Hz), 5.07 (d. 1 H, J = 9 Hz). 6.02 (br s, 1 H), 6.57 (d, 1 H, J = 16 Hz), 6.85 (d, 1 H, J = 16 Hz), 7.20 (t, 1 H, J = 7 Hz), 7.32 (t, 2 H, J = 7 Hz), 7.43 (d. 2 H, J = 7 Hz); 13C NMR (CC14) 176.6 (s), 143.0 (si, 137.3 (s), 135.2 is), 133.7 (2C, d), 128.4 (2C, d), 127.8 (d). 127.0 (d), 126.1 (3C, d), 78.1 (d), 51.4 (d), 42.4 (d), 24.5 (t), 18.4 (q), 13.9 (q), 13.6 (q), 12.9 (q); high-resolution mass measurement, obsd 310.1930, C21H2602 requires 310.1933. 7-Lactone 6: IR (CC14) 1770, 1590 cm"1; NMR (CC14) 1.00 (t. 3 H. J = 7 Hz), 1.08 (t. 3 H, J = 7 Hz), 1.19 (d, 3 H, J = 7 Hz), 1.61 (m, 1 H, J = 14, 7.…”

“…The NMR spectrum of -lactone 6 was almost identical with that of -lactone 5, with the exception that the signals at 4.16 (dq, 1 H, J = 9, 6, 6, 6 Hz) and 1.40 (d, 3 H, J = 6 Hz) in 5 were replaced by signals at 3.88 (m, 1 H, J = 9, 7, 3.5 Hz), 1.75 (m, 1 H, J = 14, 7, 7, 7, 3.5 Hz), 1.61 (m, 1 H, J = 14, 7, 7, 7, 7 Hz), and 1.00 (t, 3 H, J = 7 Hz) indicating the presence of an ethyl group at the carbon atom bearing oxygen. The coupling constants associated with the proton at 2.64 (m, J = 11, 9, 9 Hz) indicated that the relative stereochemistry of the -lactone 6 was identical with that of -lactone 5.…”

“…The presence of an additional two olefinic carbon signals in the 13C NMR spectrum was a little ambiguous due to the overlap of several signals, but their presence could be deduced because only nine other carbon signals could be observed. The olefinic region of the NMR spectrum contained signals at 7.43 (d, 2 H, J = 7 Hz), 7.32 (t, 2 H, J = 7 Hz), and 7.20 (t, 1 H, J = 7 Hz) due to the monosubstituted phenyl group, at 6.85 (d, 1 H, J = 16 Hz) and 6.57 (d, 1 H, J = 16 Hz) due to the trans disubstituted olefinic protons, at 6.02 (br s, 1 H) due to an olefinic proton, which sharpened on irradiation of a methyl signal at 1.99 (br s, 3 H), and at 5.07 (br d, 1 H, J = 9 Hz) due to the terminal olefinic proton, which sharpened on irradiation of the methylene proton signal at 2.20 (q, 2 H, J = 8 Hz) coupled also to a methyl signal at 1.01 (t, 3 H, J = 8 Hz).…”

A Computational Examination of the Uncatalyzed Meinwald Rearrangement of Monoterpene Epoxides

“…1,2-Epoxy-2,5-dimethyl-3-vinyl-4-hexene (oxido santolina triene) is a rare monoterpene epoxide, but has been found in Artemisia tridentata [15]. Neither rearrangement product, 5-methyl-3-vinyl-4-hexenal nor 8-methyl-5,7-nonadien-2-one, are apparently known natural products.…”

Santolinolide B [(2R,3S,4S)-4-hydroxy-2,5-dimethyl-3-vinyl-5-hexenoic acid lactone]. A new irregular monoterpene from Artemisia tridentata tridentata

“…1 The isolation and absolute stereochemistry of several monoterpenes lent support to this hypothesis;2"5 however, the occurrence of (2S,3fi)-santolina epoxide (3) is stereochemically inconsistent with the proposed biogenetic route. 6 If chrysanthemyl pyrophosphate is indeed the precursor of the irregular monoterpenes, then it must also occur as the IR,3S cis diastereomer since optically pure (IR,3R)frans-chrysanthemol (4) has been isolated from Artemisia ludouiciana.4…”