Transanular Interactions in Difunctional Medium Rings, 41'1. Boraalkenes CD 1 cD= 2 Bei der Synthese der 3-Alkyl-3-borabicyclo[3.3.l]non-6ene 3b-e und -nonane 4b-e nimmt 3-Methoxy-3-borabicyclo[3.3.l]non-2-en (3a), das man durch Umsetzung von 3-Allyl-3-borabicyclo[3.3.l]non-Zen mit wasserfreiem Methanol erhalt" 'I, eine Schlusselstellung ein.
Theendo-?-[(dialkylamino)methy1]-3-borabicyclo[3.3.l]nona-nes 1 and 2 have been synthesized and their intramolecular complex formation of the corresponding 2-azonia-1-borata-tricycl0[4.3.l.l~~~]undecanes 3 and 4 has been studied in the gas phase by UV photoelectron spectroscopy and in solution by llB-NMR spectroscopy. Deviations of the characteristic spectral features from those of the monofunctional bicyclic boranes 5 and amines 6 and 7 indicate that in the gas phase the (dimethy1amino)boranes with a B-alkyl substituent adopt the tricyclic form 3a-c whereas the diethylamino and the Bmethoxy derivatives l e and 2 prefer the bicyclic structure. In solution some deviations from this behavior are observed.
Synthesis of endo-7-[(Dialkylamino)methyl]-3borabicyclo[3.3. llnonanesReaction of chlorodiethylamine with the 1 -boraadamantane-THF complex affords 3-chloro-7-[(diethylamino)methyl]-3-borabicycl0[3.3.l]nonane [~~~]. With sodium meth-
The endo-?-(aminomethyl)bicyclo[3.3.l]nonan-3-ones 1-4 perties of 1-4 with those of the isochromophoric monofuncwith a primary, secondary, or tertiary amino group have been tional compounds 7-11 indicates that 1 and 2 form mixtures synthesized, and their tendency to form the corresponding with the tricyclic isomers 5 and 6, respectively, whereas 3 tricyclic amino carbinols has been investigated by theoretical and 4 show no interactions between the amino and the car-(MMX, AM1) and experimental (PE, 13C-NMR spectroscopy) bony1 group in the solely present bicyclic structures. methods. Comparison of the characteristic spectroscopic pro-
Kovacic et al.[2%31 have investigated the intramolecular interaction in endo-7-(aminomethyl)bicyclo-[3.3.l]nonan-3-ones leading to tricyclic amino carbinols. While, mainly from IR and 'H-NMR spectroscopic measurements, for the parent compound 1 the tricyclic isomer 5 has been found to prevail, for the N-ethyl derivative only the bicyclic amino ketone has been detected. We have now studied 1 and the N-alkyl and N,N-dialkyl derivatives 2-4 by different methods. As in preceding investigations ['] we have used molecular and semiempirical quantum-chemical calculations (AM1 [' I) as well as photoelectron (PE) spectroscopy[61 and NMR spectroscopy. The ketone 7 and the amines 8-11 have been included in this study as monofunctional reference compounds.nN/xC,O interaction (transanular amide resonance) in cyclic amino ketones of medium ring size has been studied by PE spectroscopy and other methodd71.
Syntheses
endo-7-(Aminomethyl)bicyclo[3.3.1]nonan-3-one[2~ (1) or 6-hydroxy-5-azatricyclo[4.3.1. 13~s]undecane(2-azahomoadamantane, 5) and endoo-7-[(ethylamino)methyl]bicyclo-[3.3.l]nonan-3-0ne[~] (2) or 5-ethyl-6-hydroxy-5-azatricyclo-[4.3.1 .13,s]undecane (6) have been prepared by the methods described by Kovacic et al. Attempts to synthesize endo-7-[(methylamino)methyl]bicyclo[3.3.l]nonan-3-one have failed. The synthesis of endo-7-[(dimethylamino)methyl]bicyclo[3.3.l]nonan-3-one (3) has proven to be more difficult than expected. Reaction of endo-7-(iodomethyl)bicy-cl0[3.3.l]nonan-3-one[~l (12) with aqueous dimethylamine in the presence of ethyldiisopropylamine at ambient temperature does not afford 3, but by transanular cyclization tricyclo[4.3.1 .03,8]decan-4-one[91 (13) is formed. The same product is obtained when 1 is treated with bromomethane[lOl at reflux temperature in ethanol in the presence of O-NHEi 2 O * N M , , 5 6 9 LO 11 potassium carbonate If, however, the methylation is performed at ambient temperature in the presence of ethyldiisopropylamine, 3 is obtained in a yield of 64%. Alternatively, 1 is reduced to the alcohol 14[111 which affords endo-7-[(dimethylamino)methyl]bicyclo[3.3.l]nonan-3-ol (15) by
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