Bicyclic quinone

The bicyclic quinone diimine 10a exhibits the same product pattern in the reaction with excess GSH as the monocyclic quinonimine 9a. Reduction results in slow formation of... 

A [4 + 2] cycloaddition is used for constructing bicyclic quinone 64, which is then reduced to -y-hydroxyme-thylcarboxylate 65. The latter is cyclized to lactone 66, which has a skeleton of naphtho[6c]furan... 

Nitric acid oxidation of the corresponding monomethoxy precursors yielded three isomeric phenanthrolinequinones, 252-254 (50HCA1080). The linear analogs 255 and 256 were prepared by cycloaddition of l-(dimethyl-amino)-3-methyl-l-azabuta-1,3-diene to the corresponding bicyclic quinones (87JOC2285). 

Several research groups have studied synthetic approaches based on cycloaddition of quinone dimethides to bicyclic quinones (disconnection c in 98). In our laboratories we have prepared the quinone 123 in which the full ring A... 

Harrowven and coworkers disclosed a short synthesis of (-)-elisapterosin B (60) and (-)-colombiasin (61) combining the Moore rearrangement and intramolecular cycloaddition reactions (Scheme 8.20) [27b]. The bicyclic quinone 126 was generated from 125 via a domino 4 i-e conrotatory ring opening 125 126/6x-e disrotatory electrocyclization... 

An interesting combination of enzymatic with non-enzymatic transformation in a one-pot three-step multiple sequence was reported by Waldmann and coworkers [82]. Phenols 125 in the presence of oxygen and enzyme tyrosinase are hydroxylated to catechols 126 which are then oxidized in situ to ortho quinones 127. These intermediates subsequently undergo a Diels-Alder reaction with inverse electron demand by reaction with different dienophiles (Table 4.19) to give endo bicyclic 1,2-diketones 128 and 129 in good yields. 

These compounds have been prepared via oxidative addition reactions between the appropriate phosphate or phosphine and either a quinone or via displacement reactions with a suitable diol. Compounds 81 and 83 were prepared by such a displacement reaction between monocyclic pentaoxyphosphorane 317 and 3-fluorocatechol or catechol in toluene, respectively. This reaction takes advantage of the chelation effect of forming a bicyclic system from a monocyclic one <1997IC5730>. Compound 82 and compound 84 were synthesized via oxidation addition between tetrachloroquinone and the respective sulfur-containing cyclic phosphate or phosphine <1997IC5730>. Compound 93 was prepared from the phosphine 318 and the diol 319 in the presence of iV-chlorodiisopropylamine in an ether solution <1998IC93>. 

Waldmann et al. used tyrosinase which is obtained from Agaricus bisporus for the oxidation of phenols to give ortho-quinones via the corresponding catechols in the presence of oxygen (scheme 33).1881 A combination of this enzymatic-initiated domino process with a Diels-Alder reaction yields the functionalized bicyclic components 164 and 165 as a 33 1 mixture starting from simple p-methyl-phenol 160 in the presence of ethyl vinyl ether 163 as an electron rich dienophile via the intermediates 161 and 162 in an overall yield of 77%. 

The autoxidation of cyclic ketones with dirhenium decacarbonyl under basic catalytic conditions produces dicarboxylic acids (68-73%) bicyclic ketones are converted into keto carboxylic acids and, when one ring is aromatic, quinones are obtained, e.g. 1-tetralone produces 2-hydroxy-1,4-naphthaquinone (93%), and H02C(CH2)4C0(CH2)3C02H (85%) is obtained from 1-decalone via a cyclic triketone [5]. 

Cycloaddition Anodically generated phe-noxy cations, o-quinones, and o-quinone methides react with olefins to bicyclic and tricyclic annelated compounds in stereoselective cycloadditions [250-252]. In the synthesis of a Euglobal skeleton, a quinone methide has been generated in situ by anodic oxidation mediated by DDQ. The cycloaddition was promoted by the use of lithium perchlorate... 

Padwa et al. (44) studied the diazo-decomposition of 119 and found that the cyclic ylide 120 could be trapped by a variety of heterodipolarophiles such as ethyl cyanoacetate (Mander s reagent) to provide aminal 121 or with benzaldehyde to generate the bicyclic acetal 122. In both cases, only a single isomer was formed, with the regiochemistry easily predicted from frontier orbital considerations. Nair et al. (45) were able to employ the highly functionalized o-quinone 125 for the trapping of carbonyl ylide 124 to provide the highly complex cycloadduct 126 in 76% yield. 

The first isolation of a derivative of 71 was reported by Sander et al. in 1998. Irradiation of quinone diazide (73) with X > 475 nm in an argon matrix at 10 K quantitatively yields 2,6-dimethylcyclohexa-2,5-diene-l-one-4-ylidene (74). Short wavelength irradiation (X > 360 nm) converts 74 into the substituted a,3-didehydrotoluene derivative 75 (Scheme 16.22). Upon prolonged irradiation 76 and (presumably) 77 are formed by Myers cycloreversion. No evidence was found for the formation of bicyclic 78. ... 

These compounds offer interesting possibilities for further elaboration as they enter into addition reactions with, for example, the 1,2-quinone (60), yielding tricyclic compounds (61) (79TL237), and their bicyclic analogues (62) combine with phenyl isocyanate to give adducts (63), which eliminate carbon dioxide to afford pyrimidine betaines (64). Similarly, dialkyl acetylenedicarboxylates produce quinolizinones (65) (Scheme 19) (79CB1585). 

Since the initial reports of the C-P-Q triads, a number of other molecules of the D-D -A or D -D-A types have been described. Triad 12, prepared by Wasielewski and coworkers, is a relative of the C-P-Q series in which the secondary donor is an aniline derivative (D), rather than a carotenoid [63]. The bicyclic bridges were introduced in order to add rigidity to the system. The fluorescence lifetime of the porphyrin moiety of 12 was found to be <30ps. This result is consistent with rapid electron transfer to the quinone to yield D-P+-QT. This result was confirmed by transient absorption measurements. The absorption results also revealed that this intermediate charge separated state decays with a rate constant of 1.4 x 1010 s-1 to a final charge separated state D+-P-Qr. Thus, the decay pathways are similar to those shown in Fig. 3 for the C-P-Q triads. This final state has a lifetime of 2.45 ps in butyronitrile (which is similar to that found for 4 in acetonitrile) [44], and is formed with a quantum yield of about 0.71. Thus, the efficiency of the transfer analogous to step 4 in Fig. 3 for this molecule is also about 0.71. 

Dyads 19 and 20 also feature a very rigid bicyclic scaffold between donor and acceptor, and show some unusual properties [98, 105]. The two molecules differ significantly only in the location of the naphthoquinone carbonyl groups relative to the porphyrin macrocycle. Dyad 19, whose quinone carbonyl groups are rela-... 

Anodically generated phenoxy cations, o-quinones, and o-quinone methides react with olefins to give bicyclic and tricyclic annelated compounds stereoselectively [359-366]. 

It is surprising that the rate of photodriven electron transfer in 17 is as great as it is. It was noted above that simple electron transfer theories predict an exponential dependence of electron transfer rates on donor-acceptor separation. Calculations based on an estimate of the donor-acceptor distance in 17 and the quantitative dependence of electron transfer on distance found for other porphyrin-quinone systems [27, 62-64] suggest that the quantum yield of formation of C-P -QA(OMe)2-Qr should be near zero. It seems likely, then, that the dimethoxynaphthalene 7t-electron system and perhaps the bicyclic bridge are playing some role in the electron transfer process. 

P. Quayle and co-workers utilized the Dotz benzannulation reaction for the synthesis of diterpenoid quinones." The authors developed a novel synthetic approach to 12-O-methyl royleanone using a simple vinyl chromium carbene complex along with a disubstituted oxygenated acetylene. The bicyclic hydrazone was converted to the corresponding vinyllithium derivative by the Shapiro reaction and then functionalized to give the desired crude Fischer chromium carbene complex. The benzannulation took place in refluxing THF with excellent regioselectivity, and the natural product was obtained in 37% overall yield from the hydrazone. 

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