Abtract: Nitrogen-and nitrous oxide-separated carbocationarboxylate ion pairs have been prepared by five different reactions: the rearrangement of N-nitroso amides, the reaction of acid chlorides with anti-diazoates, the reaction of acid chlorides with syn-diazoates, the reaction of acid chlorides with anions of N-nitroamines, and the decomposition of N-nitroso-0-acylhydroxylamines. Comparative stereochemical, I 8 0 scrambling, and product analyses have been made where common alkyl groups (1-phenylethyl), acyl groups (Znaphthoyl), solvent, and temperature are employed. The five reactions yield the same organic products, and they p r d with the same degree of retention of configuration; the reactions that were examined show the same extent of I8O scrambling. Interestingly, differences in product ratios were detected in a comparison of the nitroso amide and nitrosohydroxylamine reactions, with the latter reaction providing the larger proportion of ester. The results indicate that the structural differences built into the precursor molecules are averaged out with respect to two of the product characteristics, but not to all three. These reactions are proposed to proceed via nitrogen-or nitrous oxide-separated ion pairs. The reactions are little influenced by variables such as temperature and solvent, and the carbocations prepared in this manner exhibit a remarkably high reactivity. The relevance of these results to other methods of deamination is examined. Solvolytic (SN1)2 and deamination3s4 reactions proceed formally through carbocation intermediates, but the kind and distribution of products in the two casts can differn5 For example, the nitrous acid deamination of propylamine in acetic acid yields propyl acetate (60%) and isopropyl acetate (40%), whereas the solvolysis of propyl 4-toluenesulfonate in the same solvent yields only 2.8% of the secondary Deamination reactions can be adapted to nonpolar solvents, and under these conditions the carbocations formed can be trapped by the solvent (if certain conditions are met); they also exhibit remarkable reactivity (eqs 1 and 2).6a9738 C~H S C H~N ( N O ) S O~C F~--C~H~C H : N~ O~S C F~-~C O H S C H $ -CCHI ( 2 ) CeHsCHiCoHsWe now report on reactions designed to reveal the properties of intermediates in deamination reactions. We have examined a set of reactions utilizing chiral and '*O-labeled reactants in which different but related intermediates are formed (Chart I); we examined the N-nitroso amide decomposition, a modification of the nitrous acid approach, and four variants in the same solvent and at the same temperature. The reactions produce carbocations and carboxylate ions in common, but they differ in the inert molecule produced (N2 vs N20) and in the spatial arrangements of the key elements in the precursors (reaction 1 (2) vs 3 and reaction 4 vs 5 in Chart I).Reaction 1, the N-nitroso amide decomposition (Chart I), has previously been examined in some depth.4aJ1J2 A rearrangement leads to the anti-diazoate ester (3); subsequent reactions lead to substitution...

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A B 2To gain information regarding the stereochemical disposition at both migration termini we have prepared and isomerized the three isomeric trans-1,2-di(prop-1 '-eny1)cyclopropanes 3,4, and 5. 3 4 5The ttt isomer 3 was prepared from hexa-tvans-2,trans-4-diena1, through LiAlH, reduction, Simmons-Smith cyclopropanation, l6 oxidation of the cyclopropylcarbinol with activated Mn02, and coupling of the resultant aldehyde with ethylidenetriphenylphosphorane.*! l7 The hydrocarbon product, purified by glpc on a squalene column, had a strong infrared band at 958 cm-' and the expected mass and nmr spectral characteristics.The other isomers were obtained from trans-cyclo-propanedicarboxylate18 which through LiAIH, reduction, CeIV o x i d a t i~n , '~ and a Wittig condensation led to a mixture of 4 (995 and 712 cm-l) and 5 (713 cm-l).Isomer 3 is completely converted to cis-6,7-dimethylcyclohepta-1,4-diene (6) within 4.3 hr at 178". The nmr spectrum of the C9HI4 product showed an AB pattern ( 6~ 3.07, 6~ 2.55, JAB = 19 Hz) for the nonequivalent protons at (2-3. 6 7 8

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Die Pyrolyse bei 660‐680°C der Propargylester (I) in der Gasphase bei niedrigen Drücken liefert die Diketone (II) (72‐88% Ausbeute), die anhand ihrer NMR‐ und IR‐Daten sowie der katalytischen Hydrierung zu den entsprechenden Alkanen charakterisiert werden.