Longifolanes

Sesouiterp. dimeric auaianes absinthin (Compositae AY) longifolane (Bryoph. and Himalayan Pinus longifolia Roxb., Gymn. MI). 

Another rearrangement of the longifolane skeleton has been recorded by Lhomme and Ourisson. They have found that the keto-ester (175) is transformed into the isomeric compound (176) on treatment with boron trifluoride in benzene and they have suggested the mechanism outlined in Scheme 3. Coates... 

Longipinanes are differentiated from longifolanes whieh formally and biogeneti-cally also emerge from famesane by eleaving the C-3-C-4 bond and elosing the... 

Longifolene could not be hydrogenated over a Ni or Pd catalyst in neutral medium 43). However, it can be reduced with Pd catalyst in acetic acid (43) or with Adam s PtOa catalyst in either ethyl acetate or acetic acid (44). The product of hydrogenation consists of an approximately 1 1 mixture of two longifolanes (54) and (55) (44). In contrast, camphene is readily hydrogenated to isocamphane (56) the other epimer arising from endo addition is formed in trace quantities only (43). 

An important characteristic of medium-sized alicyclic rings is the ease with which transannular reactions arising from proximity of atoms occur (e.g. see 103). In the preferred conformation of the four-carbon bridge in the longifolane (155) and longibornane (156) systems, the proximity of the C-3, C-10 and C-2, C-9 positions, respectively has been responsible for interesting transannular reactions, both of homolytic and heterolytic types. 

Thierry, J.-C., and R. Weiss fetudes cristallographiques en serie Sesquiterpenique. I. Structures cristallines et moleculaires du bromo-3a longifolene, du bromo-3a (7pH) longifolane et du bromo-7 cyclo (3 15) longifolane. Tetrahedron Letters 1969, 2663. 

Jadhav, P. K., and U. R. Nayak Novel Hypoiodite Functionalization of Longifolol Synthesis of Longifol-7 (15)-en-5p-ol and Longifolan-3a,7a-oxide Sesquiterpenes from Jimiperus conferta. Tetrahedron Letters 1976, 4855. 

Patnekar, S. G., and S. C. Bhattacharyya Terpenoids. XCIV. Synthesis of Novel Longifolane Derivatives via Oxidation with Lead Tetraacetate. Tetrahedron 23, 919... 

Doi K, Shibuya T, Matsuo T, Miki S 1971 Longifol-7(15)-en-5jff-ol and longifolan-3a,7a-oxide new sesquiterpenes from Juniperus conferta Pari. Ifetrahedron Lett 4003-4006... 

Along with longifolane- and longipinane-types sesquiterpenes, (-h)-a-himachalene (436), (—)-P-himachalene (437) and (-h)-y-himachalene (438) have been isolated from Scapania undulata (2, 223). All himachalanes isolated are antipodal to those obtained from higher plants. 

Chart 20. Himachalanes, longifolanes, longipinanes, and sativanes found in the Hepaticae... 

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