Manool

Lobry de Bruyn-Alberda van Ekenstein reaction, 4 712 Manometers, 11 783 20 681 capacitance, 20 658-659 liquid, 20 646-647 Manool, 24 576... 

Manool 117 and manoyl oxide 118 (Structure 4.36) are found in pine oils. They are common diterpenes encountered in many essential oils. 

The conifers are an important source of diterpenoids. Several labdanes have been detected in the neutral fraction of the oleoresin of Araucaria excelsa, including manool as well as nor-labdanes [42]. Some neutral diterpenoids, such as enMabd-8, 13(E)-dien-15-ol and its acetate, were obtained after extraction of the resin of Araucaria bidwillii [43], while the normal series of the above labdanes have been isolated from Cistus creticus subsp. creticus [44]. From Pinus sylvestris, 3P-hydroxybiformene has been obtained, while from the needles of the American red wood pine (Pinus resinosa), 8,13-epoxy-labd-14-en-19-oic acid, was isolated. In Pinus nigra, labdane acids have been found to be the major acid components of its needles [45,46]. The occurrence of diterpenoids including labdanes in conifers has been published as a review of the chemistry of the order Pinales [47],... 

From the plant Agathis robusta a group of labdane isomers at C-13 have been isolated and related to 13-e/n-manool after interconvertion using lithium in diaminoethane [110]. The Hymenaea species, i.e H. ablongifolia and H. parvifolia, have been studied and enantiopinifolic acid as well as guamaic acid have been isolated, while enantio-13-ep/-labdanolic acid has been isolated from Trachylobium verrucosum [111]. 

The configuration at C-13 of the diterpenes has been a problem for many years. NMR spectroscopy using chiral shift reagents has been suggested as a method to differentiate manool from 13-epi-manool [131]. Most of the diterpenes with a saturated side chain were present as mixtures of C-13 epimers. Small differences in chemical shifts in the H and l3C - NMR spectra did not allow assignement of the stereochemistry at C-13 [132]. 

The absolute configurations of sclareol (2) and manool (5), Fig. (7), at C-13 have been determined [133]. As Hanson reported [134], the absolute stereochemistry assigned to some labdanes should be reexamined due to the enantiomers of labdanes. The biosynthetic pathways of sclareol and manool start from a geranyllinalool - type skeleton which cyclizes in a similar fashion as that described for cativic acid [135] and, via the intermediate 6, Fig. (7), sclareol is formed by hydration of 6, or manool by the loss of a proton [112,136]. 

Solvent Pimaradiene Pimarol Pimaric Isopimara- Isopimarol Isopimaric en/-Kaurene Podo- Manool... 

The investigation of potential perfumery compounds from manool has continued with the preparation of some 12-methylene derivatives [e.g. (30)]. A relatively stable ozonide (31) has been obtained from manool. The crystal structure of the ruthenium tetroxide oxidation product (32) obtained from manool has been determined. The sulphur derivatives of the perfumery acetals obtained from manool have been prepared. ... 

Compounds based on manool and sclareol have been studied for perfumery purposes for many years. The conversion of manoyl oxide (5 R = H2) and its... 

An interesting application of the method by Jeger s group d is to 8a,20-oxido-manool (5). On oxidation in aqueous dioxane the initially formed o-hydroxyaldehyde (6) suffered reverse aldolization to give the methyl ketone (7) and formaldehyde. 

The concise construction of the strobane skeleton from 13-epi-manool (Scheme 4.5) provides an example of intramolecular capture of the intermediate carbon radical.8 The acetoxymercuration step leads to two epimeric derivatives at C8 but only the (1-isomer can undergo the desired cyclisation. This occurs fairly efficiently to give one isomer whose stereochemistry has not yet been established. 

The formation of a common manool trihydrochloride from manool, sclareol, manoyl oxide, 13-epimanoyl oxide, biformene, and abienol played an important part in the structural correlation between these diterpenes. Earlier proposals had suggested an 8-equatorial chlorine atom, but in a paperclarifying the various 8,13,15-chloro-labdanes, the analogous monohydrochloride from tetra-hydroabienol was assigned the 8-axial stereochemistry (8). Dehydrochlorination of this isomer yields all three expected olefins, whilst the equatorial epimer affords only the and A -olefins. 

Bicyclic Carotenoids.— The absolute stereochemistry of a-carotene (4) has been determined by Eugster and co-workers by relating a-ionone to derivatives of manool and ambrein. Natural (-t- )-a-carotene (4) was synthesised from (-I- )-a-ionone and related by o.r.d. to several other carotenoids with this chiral centre, " ... 

The synthesis starts from the natural raw material manool, which is obtained by extraction from a tree growing in New Zealand, the so-called pink pine, Halocarpus biformis (Hooker) C.J. Quinn. Epoxidation of manool, subsequent oxidative degradation of the allylalcohol side chain to yield a ketone, and intramolecular acetalization afford the ketal [193d],... 

The natural product (-P)-agelasine D 73 has been synthesized for the first time from adenine derivative 71. The terpenoid moiety was readily available from the diterpene alcohol (-i-)-manool 69<04TL4233>. 

As was described above (see page 16), K. Wada et al. [59] have isolated the epimeric alcohols (87) and (88) from the culture filtrate of fungus Aspergillus oryzae and have established their structures and relative configurations, but their absolute configurations remained unknown. Later on, Brazilian chemists [68] accomplished the synthesis of alcohols having the structures (80) and (89) from the manool (4). The latter was epoxidised selectively at exocyclic double bond, and the mixture of epoxides (90) and... 

Although manool (4) and royleanone (95) belong to the same stereochemical series, the results of polarimetric measuring, carried out in [69], turned out to be opposite to what Brazilian chemists concluded [68], Authors [69] drew the conclusion that the natural drimenols, isolated by authors [59], belong to the normal drimane row. 

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