Notes mixture, was collected by filtration and washed with ether to give 9.5 g (63% yield) of a light yellow solid, mp 244-246°. Recrystallization from CHCl3-MeOH yielded 8.5 g of analytically pure white crystals: mp 249-250°; ir (Nujol) 3190 (NH), 1695 cm"1 (C=0, -lactam); uv (EtOH) Xmax 230 nm (log e 4.00),
It has been previously shown by others7 that upon warming related diaza olefins noncharacterizable black materials are generated. Also upon treatment of either 6 or 7 with hydride ion (NaH, xylene, reflux) rapid deg-radation occurs to give a similar black, high-melting solid (H. C. R. Taylor, unpublished results).
N-Alkylation reactions of 3-bromopyrazolo[4,3-d]pyrimidin-7-one and 3-bromo-7-chloro-and 3-bromo-7methoxypyrazolo[4,3-d]pyrimidineswere studied. Alkylations in aqueous base yielded predominately N -l alkyl products, as did trimethysilylation using hexamethyldisilazane. In contrast, alkylation with 2-chlorotetrahydropyran and sodiutn hydride in dimethylformamide or with dihydropyran and an acid catalyst in ethyl acetate yielded predominantly N-2 alkyl products. Formation of 3-lithio derivatives of N -l and N-2 alkylated 7-alkoxypyrazolo[4,3-d]pyrimidines from the corresponding 3-bromo compounds was accomplished by treatment with n-butyllithium at low temperatures. N-1 alkyl compounds yield complex mixtures of products, including those of N-dealkylation and rearrangement with rupture of the pyrazole ring. The N-2 alkylated compound, 3-lithio-7-methoxy-2-tetr~ihydropyran-2'-ylpyrazolo[4,3-d]pyrimidine, was stable and reacted with benzaldehyde in high yield.
The reaction of 8-methylcamphene (5) with haloacetic acids gives a mixture of isobornyl esters which on hydrolysis followed by dehydration with phosphorus oxychloride in pyridine affords a mixture of 8-methylcamphene (5), 9-methylcamphene (8), and 10-methylcamphene (7). Authentic samples of 8-methylisoborneol (15) and 10-methylisoborneol (19) on dehydration with phosphorus oxychloride in pyridine gave 10-methylcamphene (7) and 8-methylcamphene (5), respectively, demonstrating that dehydration occurs by way of a Wagner-Meerwein shift without the intervention of 3,2-alkyl shifts.
Notesprotons. The C-22 proton gives a signal at 210 Hz while the C-23 protons give a broader signal centered at 220 Hz.Based on the above examples, this method of assignment of conformation at C-22 appears to be sufficiently general to be considered whenever the C-20, C-22 diol system is present.The author wishes to thank Dr. Marcel Gut for supplying most of the samples. Compound II,4 and the epimeric pairs III and IV,6 have previously been reported in the literature. The chemistry of the remaining compounds (V-XII), which were obtained from Dr. Gut, has not yet been published. Their nmr spectra agreed fully with the assigned structures.
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