2- Hydroxy-1,4-naphthoquinone, reaction with

Malamidou-Xenikaki E, Spyroudis S, Tsanakopoulou M. Studies on the reactivity of aryliodonium ylides of 2-hydroxy-l,4-naphthoquinone reactions with amines. J. Org. Chem. 2003 68 5627-5631. 

When these cycloaddition reactions are carried out with alkynes, furan derivatives are formed. lodonium ylide 5, for instance, on photochemical reaction with alkynes 43, gives benzofurans 44 (86JOC3453) (Eq. 19). In a similar way, the iodonium ylide derived from 2-hydroxy-1,4-naphthoquinone undergoes a cycloaddition reaction with phenylacety-lene to yield benzofuran 45 (Scheme 16) (89LA167). 

Addition of water to quinones. The yields of the known Michael addition of water or an alcohol to a 1,4-naphthoquinone such as 5,8-dimethoxy-l,4-naphtho-qninonc arc improved by addition of an oxidant such as Fe2(S04)3 to convert the initial 2-hydroxynuphlhohydroquinone to the corresponding quinone. The presence til ll 1 rcc pert-hydroxy group interferes with the reaction. 

Lau and Gompf359 prepared a series of 2-amino-6-hydroxybenzo[d]-thiazoles and corresponding naphtho[l,2-d]thiazoles on treating 1,4-benzoquinone and 1,4-naphthoquinone with thiourea in acidic media at room temperature. At high temperature the products of the reaction with 1,4-benzoquinone are 5-hydroxy benz[d]-l,3-oxathiol-2-ones... 

Mn(OAc)3-promoted oxidative reaction of 2-hydroxy-1,4-naphthoquinone (280) with a p-enamino carbonyl compound generates a spiro-lactam (281) as shown in eq. 3.115. 

As thiazoles have significant aromatic character, they display poor reactivity in cycloaddition reactions. However, a theoretical study of the Diels-Alder reactions of a thiazole o-quinodimethane 83 with 2- and 3-bromo-5-hydroxy-naphthoquinones 84 and 85 has been carried out (Scheme 24) <2000T1701>. The findings from the PM3, molecular hardness, and ab initio (3-2 Gp) calculations of this study agree with the experimental results and support the statement that hydrogen bonding plays a crucial role on the regiocontrol of the cycloadditions. 

The aza analogues of 417, iodine-nitrogen zwitterions 419, have been prepared by the reaction of 2-amino-1,4-naphthoquinone (418) with [hydroxy(tosyloxy)iodo]arenes (Scheme 2.122) [205,562,563]. Ylides 419 show interesting reactivity upon heating, aryl migration from iodine to nitrogen occurs, giving product 420,... 

This method affords an easy access to this privileged scaffold by a [3 + 2+1] annulation catalyzed by EtjN. The mechanism of the reaction is shown in Scheme 11.22. First, the Knoevenagel reaction of aromatic aldehydes 53 with 2-hydroxy-1,4-naphthoquinone 113 affords 116 that undergoes the aza-ene reaction with the ketene aminal 114 rendering 117. Next, the intramolecular hemiaminal 118 formation and dehydration afford the corresponding benzolylimidazo [l,2-a]quinolinediones 115 in good yields (60-88%). 

Li et al. applied the ionic liquid l-butyl-3-methyl-l//-imidazol-3-ium bromide ([bmimJBr, 32) for the reaction of 2-hydroxy-1,4-naphthoquinone 29 with dimedone derivatives 31 and several aromatic aldehydes 30 to afford a tetracyclic 471-pyran 33 (Scheme 13.11) [18]. The ionic liquid was proven to be reusable four times, and the product 33 could be isolated in good yield (80-89%) by simple filtration/ recrystallization. 

Mononitration of 1-hydroxynaphthalene could be obtained by use of ammonium hexanitra-tocerate(IV) supported on silica gel in acetonitrile (Chawla and Mittal, 1985) (scheme 39). The same reaction with CAN in acetic acid give the 2,4- and 4,6-dinitro derivatives. By the same method, 2-hydroxy naphthalene is converted into l-nitro-2-hydroxy naphthalene and 4-nitro-2-hydroxynaphthalene (scheme 40). The 1-alkoxynaphthalenes can be mononitrated regioselectively in the 4-position (scheme 41). The lower reactivity of CAN supported on silica gel is also evident from the fact that naphthalene derivatives are not oxidized into 1,4-naphthoquinones. The authors noticed that no reaction could be observed when ammonium hexanitratocerate(IV) was replaced by a mixture of ammonium nitrate and ammonium cerium(IV) nitrate. Silica supported CAN has also been used for the nitration of methoxyben-zenes (Grenier et al., 1999) and less electron rich aromatic compounds like benzene, toluene, chlorobenzene and bromobenzene (Mellor et al., 2000) (scheme 42). For the less electron rich aromatics, dichloromethane is used as solvent instead of acetonitrile. In most cases, the yields are good to excellent. 

The reaction of 2-hydroxy-1,4-naphthoquinone (312) with methyl vinyl ketone has been studied. " The product isolated in the presence of secondary amines... 

Oxidation of thiophene with peracid under carefully controlled conditions gives a mixture of thiophene sulfoxide and 2-hydroxythiophene sulfoxide. These compounds are trapped by addition to benzoquinone to give ultimately naphthoquinone (225) and its 5-hydroxy derivative (226) (76ACS(B)353). The further oxidation of the sulfoxide yields the sulfone, which may function as a diene or dienophile in the Diels-Alder reaction (Scheme 88). An azulene synthesis involves the addition of 6-(A,A-dimethylamino)fulvene (227) to a thiophene sulfone (77TL639, 77JA4199). 

This enzyme [EC 1.14.99.27] catalyzes the reaction of 5-hydroxy-l,4-naphthoquinone with AH2 and dioxygen to produce 3,5-dihydroxy-l,4-naphthoquinone, A, and water. The enzyme can also use 1,4-naph-thoquinone, naphthazarin, and 2-chloro-l,4-naphthoquinone as substrates, but not other related compounds. 

Vitamin-K-epoxide reductase (warfarin-insensitive) [EC 1.1.4.2] catalyzes the reaction of 3-hydroxy-2-methyl-3-phytyl-2,3-dihydronaphthoquinone with oxidized dithiothreitol and water to produce 2,3-epoxy-2,3-dihydro-2-methyl-3-phytyl-l,4-naphthoquinone and 1,4-dithiothreitol. In the reverse reaction, vitamin K 2,3-epoxide is reduced to 3-hydroxy- (and 2-hydroxy-) vitamin K by 1,4-dithioerythritol (which is oxidized to the disulfide). The enzyme is not inhibited by warfarin. 

The solid state photochemical reaction of indole with 1,4-naphthoquinone yielded 5H-dinaphtho(2,3-a 2, 3 -c)carbazole-6,ll,12,17-tetrone in addition to 2-(3-indolyl)-1,4-naphthoquinone which was also the only product in the solution photoreaction. Solventless thermochemical reactions of indole with phenanthrenequinone in the presence or absence of zinc chloride gave 10-(lH-indol-3-yl)-9-phenanthrenol and 9,10-dihydro-9-(lH-indol-3-yl)-10-(3H-indol-3-ylidene)-9-phenanthrenol or 10,10-di-lH-indol-3-yl-9(10H)-phenanthrenone, respectively. All of these products were only obtained in trace amounts in corresponding solution reactions, and are different from the adduct 10-hydroxy-10-(lH-indol-3-yl)-9(10H)-phenanthrenone obtained in the solution photoreaction (Wang et al., 1998). 

Naphthoquinone 1-oxime (772) reacts with aminoguanidine (773) and similar compounds to give 2-aminonaphtho[ 1,2-e][1,2,4]triazine 1-oxides (774). 1-Hydroxy-naphtho[l,2-e][l,2,4]triazin-2-ones can be prepared in an analogous reaction <78HC(33)189, p. 728). 

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