Naphthalene-2 -one

Complex hydrides have been used rather frequently for the conjugate reduction of activated dienes92-95. Just and coworkers92 found that the reduction of a,ft-unsaturated ketene 5,5-acetals with lithium triethylborohydride provided mixtures of 1,4- and 1,6-reduction products which were transformed into enals by treatment with mercuric salts (equation 27). Likewise, tetrahydro-3//-naphthalen-2-ones can be reduced with L-Selectride to the 1,6-reduction products93 -95 this reaction has been utilized in the stereoselective synthesis of several terpenes, e.g. of (/ )-(—)-ligularenolide (equation 28)95. Other methods for the conjugate reduction of acceptor-substituted dienes involve the use of methylcopper/diisobutylaluminum hydride96 and of the Hantzsch ester... 

Oxidation of several 1,1-bisphenols 78 with IBD gives spirobenzofuran derivatives of general formula 79 (Eq. 21). This approach, when applied to benzylidine l.l -bisnaphthols 80, leads to a stereospecific cyclization, thereby forming the less hindered naphtho[2,l-fi]furan-2(l//)-spiro-r-(2//)-naphthalene-2 -ones (82) [80JCS(P1)1978,80JCS(P1)1986]. The conversion 80 to 82 probably occurs through intermediate 81 (Scheme 25). 

Further bromination of 3,4,6-tribromo-5-hydroxybenzo[6]thio-phene affords the 2,3,4,6-tetrabromo derivative in the absence of acetate ion, and 3,4,4,6-tetrabromo-4,5-dihydrobenzo[6]thiophen-5-one in the presence of acetate ion. 421 On treatment of 3,4-dibromo-, 4,6-dibromo-, 3,4,6-tribromo-, or 2,3,4,6-tetrabromo-5-hydroxybenzo-[6]thiophene with nitric acid in acetic acid, the corresponding unstable orange crystalline 4-bromo-4-nitro-4,5-dihydrobenzo[6]thio-phen-5-one is obtained.152,421 Hence, once both positions ortho to the hydroxyl group in 5-hydroxybenzo[6]thiophene are occupied by bromine, the properties of these compounds are analogous to the properties of l-bromo-2-naphthol which, on bromination in acetic acid in the presence of acetate ion, affords l,l-dibromo-l,2-dihydro-naphthalen-2-one whereas, in its absence, it affords l,6-dibromo-2-naphthol.616 The behavior of l-bromo-2-naphthol and its derivatives on nitration is similar to that of 4,0-dibromo-5-hydroxybenzo[6]thio-phene and its derivatives.162,616... 

Sodium bis(2-methoxyethoxy)aluminum hydride (S)-6-Fluoro-l-isopropyl-3,4-dihydro-lH-naphthalen-2-one... 

To the mixture 22.7 g (0.54 mol) dry lithium chloride and 100 mL THF at -15°C was added 160 mL 2 molar lithium diisopropylamide (0.32 mol) in heptane/THF/ethylbenzene was added. Then a solution of 36.6 g (0.16 mol) N-[3-(lH-benzimidazol-2-yl)-propyl]-N-methylacetamide in 140 mL toluene was added, the solution was stirred for 2 hours, and a further 155 mL toluene was added. (S)-6-Fluoro-l-isopropyl-3,4-dihydro-lH-naphthalen-2-one (29.9 g, 0.15 mol), in 15 mL toluene was added. After stirring at -10°C for 4 hours, the resulting solution was added to 200 mL ice water. The pH of the resulting mixture was adjusted to 7-8 by addition of a 71 g concentrated hydrochloric acid. The organic layer washed with water, then the solvents removed under reduced pressure to give 96 g of (lS,2S)-N-[3-(lH-benzimidazol-2-yl)propyl]-... 

Flash-vacuum pyrolysis of l,l,4,5,6,7,8-heptafluoro-l,2-dihydrocyclobuta[a]naphthalen-2-one (550 C) resulted in carbon monoxide extrusion and concomitant formation of the correspond-... 

---