Naphthalene cores

For molecules XVI —XVIII it is predicted that bond lengths of the naphthalene core are almost the same as those of the free naphthalene molecule, and in the other region of the molecule marked bond fixations are observed . The most stable ground-state geometry of XVI corresponds to the aromatic model proposed by Lo and Whitehead . Molecules XVI and XVII have been synthesized by Trost and Bright and Boekelheide and Vick , respectively. The present results are in good qualitative agreement with the available experimental information. 

Sometimes transformation of aromatic componnds into ion-radicals leads to stereochemically unusual forms. Octamethylnaphthalene is a nonplanar molecule twisted around the bond that is common for the two six-membered rings. The nitrosonium oxidation results in the formation of the cation-radical with the centrosymmetric flatten chairlike geometry (Rosokha and Kochi 2006). According to the authors, such a skeletal transformation improves the overall planarity of octamethylnaphthalene. For example, the mean deviation of the carbon atoms in the naphthalene core for the flatten chairlike cation-radical (0.007 nm) is less than half of the corresponding value for the neutral twisted parent (0.016 nm). Within this flatten carcass of the anion-radical, the spin density can be delocalized more effectively. 

Let s move to the other end of the spectrum and analyze prior art genus 1. This Markush contains 14 hypothetical members, all of which share a common naphthalene core. The variability of the Ra is not great, containing the possibility of hydrogen, methyl and //-propyl only. Given these facts, it is quite likely that Petering would be controlling and Markush 1 would anticipate the later claimed species compound 4 and thus render it nonpatentable. 

Table 11.1 Redox properties of alkylamino-(i, ii, iii, and iv) NDIs bearing different patterns of donor and acceptor substituents at the naphthalene core.a...

The minimal active space needed to describe the electronic structure of the NDI moiety includes the five occupied and five unoccupied 7t-orbitals of the naphthalene core and four lone pair orbitals of the carbonyl groups. The 57t[4n]57t active space contains 14 electrons and electronic transitions arise from seven states. Only two of the seven states, 1 1 B2u and 1 B3U, show transitions in the region of interest between 320 and 420 nm. Other transitions have no effect on the bands in this region and hence were not considered. The main features in the experimental absorbance spectrum were reproduced using the most intense Frank-Condon transitions (Fig. 15). The calculated spectrum (dashed lines) showed a red shift of 9 nm relative to the experiment, which may be due to the representation of each transition by only two charges, and also due to the neglect of other transitions. 

Meinwald et al. (76JA6643) described reactions with sodium hydroxide and lithium phenylamide leading to the formation of sodium 1-naphthalenesulfonate (69) and 1-naphthalenesulfonamide (70), respectively. Again, the negatively charged fragment of the reagent attacks the sulfur atom, followed by protonation of the atom of the naphthalene core (Scheme 13). 

The treatment of 1,8-dilithionaphthalene (18) with dimesitylboron fluoride gave heterocyclic anion 80 with counterion [Li(THF)4] or [Li(Py)4] (02MI1982). The counterion character depends on the solvent used for recrystallization of the primary product. Salts 80 were characterized by their NMR spectra proving the presence of a symmetrically substituted naphthalene core. While 80 with the [L1(THF)4] counterion is unstable and quickly looses THF at room temperature, crystals with the [Li(Py)4] counterion are sufficiently stable to be subjected to the X-ray diffraction analysis (Scheme 16). 

Statins can be classified as natural statins and synthetic statins. Lavastatin, simvastatin, and pravastatin are the first three natural statins to reach the market. Lavastatin and pravastatin are natural products isolated from fermentation broths, while simvastatin is a semisynthetic statin derived from lavastatin. Fluvastin was the first truly synthetic statin brought to the market by Sandoz pharmaceutical company (now part of Novartis), and it was obtained by replacing the hexahydro-naphthalene core stiucture of the natural statins with the indole nucleus [5]. It was the discovery of fluvastin that opened up the opportunity of more potent synthetic statins including atorvastatin, the most prescribed drug in the world. 

Lee, S. K. Naito, Y Shi, L. Tokita, M. Takezoe, H. Watanabe, J. Mesomorphic behaviour in bent-shaped molecules with side wings at different positions of a central naphthalene core. Liq. Cryst. 2007, 34, 935-943. 

S.K. Lee, M. Tokita, H. Takezoe, J. Watanabe, Effect of molecular structure on smectic phase structures in two homologues series of bent-shaped molecules with asymmetric central naphthalene core, Ferroelectrics 365 (2008) 1. 

Racemate and mesomer forms of the interesting elaborated thiophene-based naphthalene-cored double helicenes 18 have been synthesized using a one-pot photocycUzation of l,l,2,2-tetrakis(dithieno[2,3-l 3 2 -[Pg.9]

Tetra(3-thienyl)ethene (30) in the presence of iodine upon 313 nm irradiation led to (31) as the main product, while 350 nm irradiation afforded the tetrathienonapththalene (32) in 20% yield/ Irradiation of (33) in the presence of iodine in henzene afforded the racemate (34) and the meso-isomer (35) of the thiophene-hased naphthalene-cored double helicenes/ The enantiomers (34) were isolated hy using a semipreparative scale chiral column. The oxidative photocyclization of (36) in a batch photoreactor gave the aza[6]helicene (37) in 19% yield, while in a flow-micro-photoreactor the yield was up to 55%/ ... 

Bent mesogens with the comparatively small bent-angle naphthalene core also show interesting dissipative structures [147-150]. (l,7)-nS-PIMB that has 1,7-dihydroxydiamine naphthalene as the central core is raie example. 

The transition-metal-mediated aromatic ring construction reaction via the [2 -I- 2 -I- 2] cycloaddition reaction is not restricted to the formation of a single benzene moiety. As already discussed within the intramolecular version of this reaction [i.e., the syntheses of (+)-viridin (47) and the angucyclines 58-60], this pivotal cycloaddition reaction can be used for the synthesis of naphthalene or anthracene moieties whenever it is embedded in a sequence of consecutive reactions. However, a more straightforward entry to the naphthalene core was realized during synthesis of the lignans taiwanin C (100) and E (101) (Scheme 7.21) [30]. 

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