2- Acetyl-1,4-naphthoquinone

With both naphthoquinones, remarkable side reactions have been observed (Scheme 37). Although Bruce had already studied the photoinduced acylation of ffie acetylated naphthoquinone 61, for which he assigned the corresponding acylated hydroquinone pair (vide supra)P more recent studies revealed that further 1,5-acyl migration of the 2,5-regioisomer (63 —> 114) occurred. From ffie photoacylation of the meffioxy derivative 108, diacylated products (115) were obtained with acetaldehyde and benzaldehyde, respectively. 

The reaction of 2-anilino-l,4-naphthoquinone 374 with benzoylacetic acid hydrazide gives 3-hydrazino-pyrazolyl derivative 375, that is acetylated to produce 5-[[l,4-dihydro-l,4-dioxo-3-(phenylamino)-2-naphthalenyl]sulfonyl]-3-methyl-6-phenyl-5/7-pyrazolo[5,l-c][l,2,4]triazole 51. This latter derivative is also obtained in 51% yield from reaction of 374 with benzoylacetic acid hydrazide in the presence of a mixture of acetic acid-sodium acetate <2004PS(179)1907> (Scheme 39). 

Lawsone (Cl Natural Orange 6 Cl 75420), also known as henna and isojuglonc. occurs in the shrub henna [Lawsone alba). Lawsone has been identified as 2-hydroxy-1.4-naphthoquinone. It has been synthesized by the Thiele acetylation of 1.4-naphthoquinnne followed by hydrolysis and oxidation. 

In addition to these commonplace substrates, only a few extraordinary educts have been used in iron-catalyzed DA reactions, such as the naphthoquinones investigated by Brimble and McEwen [75]. Whereas the application of FeCl3 and a chiral bisoxazoline ligand gave only a 25% yield and no chiral induction in the reaction of 2-acetyl-l,4-naphthoquinone with cyclopentadiene, the corresponding copper(II) triflate gave a 66% yield and moderate enantioselectivities (up to 50% ee). Another example was reported by Shibasaki s group in which the 2-alkoxy-l,3-butadiene 40... 

The analogue of 1 hydroxylated at C-6, e.g. 3-deoxyrabelomycin (20), was synthesized by Kraus and Wu using the excellent Michael acceptor properties of the extremely electron-deficient 3-acetyl-5-methoxy-1,4-naphthoquinone (17) [31, 32] (for related reactions of Eugster et al. compare [33]). The addition of 5-methyl-l,3-cyclohexadione (18) proceeded at 20-25 C without catalyst to afford adduct 19 after methylation. The subsequent intramolecular Michael-type reaction followed by elimination of methanol afforded more drastic conditions (NaOH, MeOH, 140 °C) and gave relatively low yields (27%) of a tetracyclic intermediate which was demethylated in the usual manner with AICI3 to yield 3-deoxyrabelomycin (20, Scheme 6). 

Synthetically, compound 152 was prepared by the Friedel-Crafts procedure from furan-3,4-dicarbonyl chloride and a tetralin derivative (85JCR (S)338). 1,4-Dihydro-l,4-epoxy-5,8-naphthoquinone, when treated with 3,6-di(2-pyridyl)-l,2,4,5-tetrazine, yielded the quinone 153 (75JCS(P1)1339) derivatives of 153 are also known (74CC1034). The parent compound (153) is a stable derivative of the unstable isobenzofuran. Finally, 3-acetyl-2-furyl-1,4-benzo- (or -naphtho-) quinones are isomerized photochemically in aprotic solvents into the quionones 154 (66HCA1806). 

Synthetically, 2,3-dihydro-l,4-benzoxazine-6,7-diones (391) can be prepared from 2,5-bisanilino-3-acetyl- (or methoxycarbonyl)-l,4-benzoquinones and substituted 2-hydroxyethylamines (73T2881). 2-Amino-3-aziridino-1,4-naphthoquinone, when heated in aqueous sodium hydroxide, is claimed to give 392 (69FES732), and the benzo analog was prepared from 2,3-dichloro-... 

Beagley, B, Curtis, ADM, Pritchard, R G, Stoodley, R J, As3munetric Diels-Alder reactions. Part 6. Regio- and stereo-selective cycloadditions of 5- 2, 3, 4, 6 -tetra-0-acetyl-p-D-glucopyranosyloxy)-l, 4-naphthoquinone, J. Chem. Soc. Perkin. Trans 1, 1981-1991, 1992. 

Other polycyclic systems such as naphthoquinones also undergo the dienone-phenol rearrangement. Thus, acetylation of naphthalene-l,4,5(8H)trione 328 with AciO containing an acid (H2SO4, HCIO4) resulted in a rearrangement yielding naphthoquinone 329301-303 (equation 157). 

The aziridine 9, prepared from 2,3-dichloro-l,4-naphthoquinone by displacement of the first chlorine with alanine, acetylation, and replacement of the remaining chlorine with aziridine, is converted into the benzoquinoxaline dione 10 on treatment with acid. ° 2-Amino-3-chloro-l,4-naphthoquinone is converted by successive treatment with chloroacetyl chloride and diethylamine into the benzoquinoxaline trione 12. The intermediate 11 is not isolated, but with other... 

Naphthoquinone (122)62 63 64 on reductive acetylation afforded diacetate (123). Selective basic hydrolysis afforded monoacetate (124). This on benzylation followed by basic hydrolysis and alkylation with chloroacetone yielded compound (125). Its cyclization was attempted with tetrafluroboric acid in ether. The resulting compound (126) was immediately oxidized with selenium dioxide to Mansonone F (120). 

Modiput Rigid, Modipur RiM, Modipur Semifiexibie, Modipur TPU. See Polyurethane resin Moduian . See Acetylated lanolin Mogeton G. See 2-Amino-3-chloro-1,4-naphthoquinone Mogui L. See Carbon black Mohave yucca extract. See Yucca schidigera extract... 

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