Tetralin nucleus

The helioporins, a group of marine diterpenes with antiviral and cytotoxic properties, are structurally closely related to the (seco-) pseudopterosins and all possess a characteristic benzodioxole unit [29]. Their stereostructure was assigned as shown in Fig. 4 with a cfs-relationship of the two benzylic sidechains at the tetralin nucleus. 

He considered as mono-aromatics molecules with one or more non-condensed benzene nuclei, e.g. alkyl-benzenes, tetralin-derivatives, diphenyl. Di-aromatics he defined as molecules with one or more naphthalene nuclei not condensed with each other or with a benzene nucleus. 

Portas CM, Thakkar M, Rainnie D, McCarley RW. Microdialysis perfusion of 8-hydroxy-2-(di- -propylamino)tetralin (8-OH-DPAT) in the dorsal raphe nucleus decreases serotonin release and increases rapid eye movement sleep in the freely moving cat. J Neurosci 1996 16 2820-2828. 

The Mills-Nixon hypothesis had, as its foundation, certain differences in the chemical behaviour of indan (3) and tetralin (4) from which a localization of the aromatic 7r-bonds was predicted to occur in the direction depicted by la rather lb. The original experimental evidence upon which the effect was based was shown to be erroneous, but calculations at various levels of theory indicated that aromatic bond localization should exist and become more pronounced as the size of the annelated ring decreases In essence one can recognize that the structure of benzene has a symmetry such that both Kekule structures must contribute equally. With Q tetralin (4) (and the lower homologues) no such symmetry requirement exists and ring annelation could induce bond length alternation within the arene nucleus. As the strain imposed by the fused ring increases, the Mills-Nixon effect should increase. The hypothesis has been the subject of considerable discussion and the controversy is far from settled. 

Catalytic hydrogenations over CojfCOjg (using Hj and CO) or with stoichiometric quantities of preformed hydridocarbonyl complex CoH(CO)4 are useful for the partial selective reductions of polycyclic aromatic compounds. Isolated benzene rings are not affected. Naphthalene is reduced to tetralin, at 200°C under a pressure of 20 X 10 kPa and anthracene to 9,10-dihydroanthracene (99%). The substituted phenanthrene nucleus is stable under these conditions as illustrated by hydrogenation of perylene 1 and pyrene 2. ... 

In the mass spectra of compounds (1 5) and (36), as shown in Chart 8, not only the molecular ion peaks at m/z 428 but also other prominent ion peaks at m/z 260, 215, 203, 181 and 168 were common to both compounds. The mass spectra of analogous lignans have been reported by Duffield and Pelter (ref. 38). Therefore each fragment ion was assigned as shown in Chart 8b. The above results show that compound (1 5) has a trimethoxyphenyl group and a tetralin ring, and that a methoxy and a methylenedioxy group on the benzene nucleus. 

Numerous tryptamines bind with high affinity at 5-HTia receptors, but most are notoriously nonselective. One of the most selective 5-HTia receptor agonists is the aminotetralin derivative 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH DPAT), and its early discovery was significant in advancing an understanding of 5-HTia receptors. Furthermore, because the structure of 8-OH DPAT is similar to that of 5-HT (8-OH DPAT/serotonin), its activity indicated that an intact indole nucleus was not required for 5-HT ia actions. Although numerous 8-OH DPAT derivatives have been reported, none is used therapeutically because of low oral bioavailability. This has led to efforts to develop novel aminotetralins with greater oral availability. 

Methylation of naphthalene and tetralin therefore can be accomplished only in very poor yields. Similarly such reactive heterocyclic aromatic substances as furan and thiophene, have not been alkylated successfully by the Friedel-Crafts method. Deactivation of the furan nucleus by the carboxyl group of furoic acid, however, makes alkylation by the Friedel-Crafts procedure feasible and useful (see Table XV, p. 76). 

---