Diterpenoids. XXXII. Labda-8,14-dien-13β-ol

Abstract

The 13s compound 13-epiisomanool (labda-8,14-dien-138-01) has been synthesized and its optical rotation compared with that of the 13R isomer (isomanool) in order to correct errors in the literature.The 13s compound labda-8,14-dien-13P-01 (1) has been reported1 (" 13-epiisomanool") to be an oil, [a], -I-27.5" ([4], $80). The rotation of this compound, reputedly lower than that of the 13R epimer (2) ("isomanool"), was used erroneously to assign the C 13 stereochemistry to a number of compounds in this series.$ The results have been commented upon.' § During a survey of optical rotation and structure in the labdan~ids,~ we calculated that compound (1) should have a molecular rotation at 589 nm of $260 units, and that it should have a larger positive rotation than epimer (2). Compound (1) is entry 103 in the earlier paper,3 while (2) is entry 102, with the compounds now renamed to meet modern nomenclature requirement^.^The discrepancy between observed and calculated rotations for (1) was so great that it was considered3 that either the compound did not have the assigned structure or else its optical rotation had been incorrectly determined.Compound (1) ("isoepimanool") has also been isolated from a natural sources but no rotation was reported.We now record the synthesis of compound (1) from 13-epimanool (3). Isomerization of the 8(17) double bond of (3) under acid conditions is attended with considerable rearrangement of the allylic alcohol, but basic conditions using lithium * Part XXXI, Aust. J. Chem., 1973, 26, 209. t Chemistry Department, University of Queensland, St. Lucia, Qld. 4067.f The workers in reference 1 made two errors which fortuitously compensated. They had the rotations of (1) and (2) in the wrong order, but they took (-)-linalool to be S and it was not until later (Cornforth, R. H., Cornforth, J. W., and Prelog, V., Liebigs Ann., 1960, 634, 197) that (-)-linalool was proved to have the R configuration.$ The Italian workers misapply the R,S nomenclature in some instances.

Extreme promiscuity of a bacterial and a plant diterpene synthase enables combinatorial biosynthesis

“…Given that KgTS does not alter the decalin ring core structure, this further indicates that the DTC product has the same C9 and C10 configuration as normal CPP ( 3 ). Accordingly, the SsSS product is (9 R ,10 S )-labda-7,14-dien-13-ol ( 31 ), which has been previously reported (Carman et al, 1973), and the KgTS product is (9 R ,10 S )-labda-7,13(16),14-triene ( 32 ), which also has been previously reported (Maskovic et al, 2013). However, biosynthetic routes to 31 and 32 were not previously known.…”

The roots of Salvia rhytidea: a rich source of biologically active diterpenoids

“…The structures (Figure 1) of the resulting compounds; sahandinone (1, 1.0 g), 12-deoxysalvipisone (2, 20 mg) (Jassbi et al 2006), miltirone (3, 750 mg) (Hayashi et al 1970;Houlihan et al 1985), 7α-acetoxyroyleanone (4, 100 mg) (Tezuka et al 1998), labda-7,14-diene-13-ol (5, 10 mg) (Carman et al 1973;Wu & Asakawa 1987;Jassbi et al 2002) were elucidated using spectral data including EI-MS, 1 H-and APT-13 C NMR, HSQC, COSY and HMBC and with comparison with the abovementioned literature data. The structure of compound 5 was elucidated by comparing its Downloaded by [University of Cambridge] at 17:32 17 June 2016 mass and NMR spectral data with those reported in the literature (Carman et al 1973;Wu & Asakawa 1987;Jassbi et al 2002).…”

Sesqui- and Diterpenoids from Tahitian and Japanese Liverworts Jungermannia species

“…Moreover, (13S)-hydroxy-8,14-labdadiene (8) [12][13][14], entverticillol (9), ent-12-epi-verticillol (10), ent-isoverticillenol (11) and ent-verticillanediol (12) [15] were isolated. Their physical and spectral data were identical with those of references data and/or authentic samples.…”

“…1) collected in Oita pref. resulted in the isolation of a new labdane diterpenoid 13-hydroxy-8,14-labdadien-17-al (14), and known cuparene-type sesquiterpene ketoalcohol, rosulantol (13) [16], (+)-(9S*,13R*)-dihydroxylabda-8(17),14-diene (15) [17], 13-hydroxy-7-oxo-labda-8,14-diene (16) [18], and ent-13-epi-sclareol (17) [19]. Their structures were determined by comparison of the spectral data of the isolated compounds with those of the references.…”