The conversion of 5-methoxy-and 5,7-dimethoxy-1,4-naphthoquinones into their 3-acetyl derivatives is described. A key step is the Fries rearrangement of 1,5-dirnethoxy-4-acetoxynaphthalenes to the corresponding 3-acetyl-4-naphthols with boron trifluoride-diethyl ether. Alternative Fries rearrangement of I -acetoxy-4-hydroxy-5-methoxynaphthalenes gave the 3-acetylquinols, involving meta migration of the acetyl group. A convenient new synthesis of 2-acetyl-l,4-naphthoquinone is also reported.The naphtho[2,3-c]pyran ring system occurs not infrequently in Nature as derivatives of the 5,10-quinone. Examples are the eleutherins,' the nanaomycins,2 and the p r~t o a p h i n s .~ Certain analogues lacking oxygen(s) in the aromatic ring have been synthesised using 2-acetyl-1,4-naphthoquinone (1) as starting material; for example, 9-deoxykalafungin (4) and 7,9-dideoxyquinones A (5) and A' (6),' the latter being derivatives of the protoaphins. Preparation of the natural products themselves requires appropriate regiospecific aromatic oxygenation of 2-acetylnaphthoquinone. We describe here syntheses of 3-acetyl-5-methoxy-1,4-naphthoquinone (2) t and the corresponding 5,7-dimethoxy analogue (3),7 and are currently investigating the use of these in the formation of several naturally occurring quinones or their derivatives. In the course of this work, an unusual Fries rearrangement was established.to the product was supported inter alia by a sharp lowfield singlet at 6 13.46 in its 'H n.m.r. spectrum due to the strongly hydrogen bonded hydroxy group. Oxidation of this compound with ceric ammonium nitrate gave rise to the desired 3-acetyl-5-methoxy-1,4-naphthoquinone (2) in an overall yield of 67% from (7). 0 ( 7 ) R = H ( 8 ) R = OMe M e 0 OH R OMe ( 9 ) R = H (10) R = OMe ( 4 ) ( 1 ) R ' = R~= H ( 2 ) R'=OMe, Rz:H ( 3) R'= RZ = OMe 0 Me ( 5 ) R' = O H , R~ = H ( 6 ) R 1 = H , R 2 = O H Results and DiscussionJuglone methyl ether (7) was reductively monomethylated at the less hindered oxygen to give the naphthol (9) using sodium dithionite followed by treatment with dimethyl sulphate and potassium carbonate in acetone. The corresponding acetate (1 1) was treated with boron trifluoridediethyl ether at 60 "C for 30 min to give the product (13) of Fries rearrangement, together with deacylated material (9) which could be recycled, thereby providing a high yield of (13). The assignment of structure (13) t Compound (2) is already known.6 However the yield (34%) in the final step made an alternative route desirable for further synthesis. O/H.. M e 0 0 A c R ' & M e R 03 OMe OMe (11) R = H (12) R = O M e (13) R = H (14) R OMe 5,7-Dimethoxy-1,4-naphthoquinone (8) could be converted similarly into its 3-acetyl derivative (3) via the sequence (8) --+ (10) -(12) -(14) -(3). Assignment of struc ture (10) to the product of reductive monomethylation of (8) rested on a comparison with the conversion of (7) into (9) and also the appearance of a sharp, lowfield, concentrationindependent singlet at 6 8.72 for the hydrogen-bonded hydrogen [the corr...

Octanol/water partition coefficients (log P) for a series of dialkyl alkylphosphonates, dialkyl alkylphosphonothionates, and an alkyl alkylphosphinate have been estimated using reversed‐phase high‐performance liquid chromatography. The test compounds proved to be readily amenable to the chromatographic procedures employed, although the more lipophilic compounds appeared to be more tolerant to variations in the chromatographic conditions and methods of data handling than were the less lipophilic compounds with regard to the precision and accuracy of the log P values obtained from the retention data. The methodology was validated by carrying out shake‐flask experiments with two of the test samples. The rank order of log P values obtained was reasonably predictable, based on the sizes of the alkyl substituents present. The enhancement of lipophilic character attributable to replacement of oxygen by sulfur in the PO group is also evident from the results. The data for the phosphonates permit the calculation of a value for the hydrophobic fragmental constant for the OPO2 group (f = −2.79).

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Das aus dem Naphthochinon (Ia) erhältliche Derivat (Ib) wird über die Stufen (IIa), (IIb), (IIIa) in das (IIIa)‐Reduktionsprodukt (IIIb) übergeführt, dessen Oxidation a) mit AgO das (leicht instabile) Chinon (VI), b) mit 4 mol des Ce‐Salzes (V) dagegen die gewünschten Naphthopyranchinone (VIa) + (VIb), die dieselbe Stereochemie wie Chinon A (VIIa) bzw. Chinon A′ (VIIb), Derivate der Blattlaus‐Pigmente Protoaphin‐fb bzw. ‐sl, aufweisen.