Interest in 2-aminofluorene and some of its derivatives in cancer research, hope of finding biologically interesting new substances, and curiosity about certain new or little explored series of fluorene compounds, led us first to attempt a better preparation of some simple derivatives which, even when available commercially, are sometimes in a state of purity which is belied by their cost. We can report a significant increase in yield with improvements in e& ciency and convenience for several known compounds as indicated in the experimental section.The derivatives discussed below are either new or were prepared by a better or more convenient method than so far reported.Since triethylphosphate2 is an outstanding dialkylating (1) and good monoalkylating agent for certain primary aromatic amines, we tried its action on 2-aminofluorene. A ratio of 3 moles of amine to 2 of the phosphate gave a high yield of 2-N , N-diethylaminofluorene. Extraction of the reaction mixture and use of acetic anhydride were not required. A final fraction, representing a 2 % yield, was found to be 2-N-ethylaminofluorene (2). Dialkyl alkylphosphonates apparently have not been used as alkylating agents for aromatic amines. Diethyl ethylph~sphonate~ was reacted with 2-aminofluorene (one mole pf amine to two of the phosphonate), with a quantitative crude yield, giving 98% of pure product. No trace of monoalkylated compound was detected.The yield of 2-K, N-dimethylaminofluorene has been reported from 22 % (crude yield with dimethyl sulfate alone) (3) to about 92% by way of the trimethylammonium iodide compound (4). The highest yield obtained with use of dimethyl sulfate was 50-60 % (5). Our results with triethyl phosphate suggested use of trimethyl phosphate in a similar reaction. Convenience and yield recommend this as the best preparative method.N-2-Fluorenyl-p-toluenesulfonamide (6, 7) was methylated with dimethyl sulfate. Attempts to hydrolyze the tosyl group with concentrated sulfuric acid, successful with some other derivatives of aminofluorene (6) resulted in a product, apparently 2-N-methylaminofluorene-~-sulfonic acid, isolated as the methyl ester.2-N-Methylaminofluorenone was made from 2-aminofluorenone in a 94 % over-all yield, by way of the N-p-tosyl and N-methyl-N-p-tosyl derivatives.
We have been continuing a study1 of the effects of certain substances on gastric secretion in the pylorus-ligated rat. Davenport et al.f1 reported the inhibitory effects of AT-ethylmaleimide and iodoacetamide on gastric secretion in vitro. More recently, Hollander3 confirmed and amplified this observation in vivo: topical application of solutions of these substances to canine gastric mucosa resulted in secretory inhibition. In this study we have investigated the inhibitory effect on gastric secretion, in vivo, of injected Y-ethylmaleimide, N-2fluorenylmaleimide (new substance, m.p. 187 •5-188°, cor.), ß-mercaptoethylamine hydrochloride"]• and the closely related 2-aminoethyhsothiuronium bromide hydrobromide (AET). Since we found a decrease in secretory activity with each of these separately, we devised experiments seeking possible ' neutralizing ' effects of the sulphydryl type compounds on subsequently injected maleimides. There appears to be such an effect. Materials and MethodsSprague-Dawley rats (250-300 g) fasted for 72 h and deprived of water just preceding the operation, were lightly anaesthetized with ether and the pylorus of each was ligated (Shay4 preparation).
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