The structural and conformational properties of 1-amino-1-ethynylcyclopropane as studied by microwave spectroscopy and quantum chemical calculations

Microwave Spectrum, Conformational Composition, and Intramolecular Hydrogen Bonding of (2-Chloroethyl)amine (ClCH2CH2NH2)

“…A similar situation is found in H 2 NCH 2 CH 2 NH(CH 3 ) . The oxygen atom accepts a H atom in H 2 NCH 2 CH 2 OCH 3 . , This is also the case for one of the preferred conformers of amino acids exemplified by glycine − and alanine. , π-Electrons are involved in a number of cases such as H 2 NCH 2 CHCH 2 , − H 2 NCH 2 CH 2 CHCH 2 , 1-amino-1-ethenylcyclopropane, H 2 NCH 2 CCH, H 2 NCH 2 CN, , H 2 NCH 2 CH 2 CN, H 2 NCH 2 CH 2 CCH, and 1-amino-1-ethynylcyclopropane . Pseudo π-electrons are acceptors in (aminomethyl)cyclopropane, while the π-electrons of the phenyl group are active in intramolecular H bonding in, for example, amphetamine …”

“…11,12 π-Electrons are involved in a number of cases such as H 2 NCH 2 CHdCH 2 , 13À16 H 2 NCH 2 CH 2 CHdCH 2 , 17 1-amino-1-ethenylcyclopropane, 18 H 2 NCH 2 CtCH, 19 H 2 N-CH 2 CtN, 20,21 H 2 NCH 2 CH 2 CtN, 22 H 2 NCH 2 CH 2 CtCH, 23 and 1-amino-1-ethynylcyclopropane. 24 Pseudo π-electrons 25 are acceptors in (aminomethyl)cyclopropane, 26 while the π-electrons of the phenyl group are active in intramolecular H bonding in, for example, amphetamine. 27 An important finding made for the majority of the above examples is that both H atoms of the amino group form internal NÀH 3 3 3 X hydrogen bonds, which results in two conformers, similar to rotamers III and IV of the title compound discussed below.…”

Productive Syntheses of 1-Ethynylcyclopropylamine and 1-Ethynylcyclobutylamine¹

“…Various oligosubstituted analogues of 3 with complex substituents at the acetylene terminus have been prepared either from cyclopropanone equivalents under different conditions, by selective dihalocyclopropanation of appropriately functionalized enamines or via cyclopropene intermediates. 9 While the structural and conformational properties of the parent 3 had been published without preparative details by us before, 10 the (1-ethynylcyclobutyl)amine (5) (Figure 1) has been unknown so far. A number of compounds with a (1-ethynylcyclobutyl)amine moiety have demonstrated an enhanced anticancer activity.…”

Hydrogen Bonding—New Insights

“…Therefore, several model molecular systems have been chosen to probe the water-mediated interactions in biomolecules and a large amount of experimental and theoretical work has been published over the years on this subject [78,138,[251][252][253][254][255][256][257][258]. Since phenol is the simplest aromatic alcohol resembling chromophore of an aromatic amino acid, hydration of phenol molecules has been studied to understand H-bonding and solute-solvent interaction in biological systems.…”

“…Unconventional intramolecular hydrogen bonds involving the double or triple bonds p-electron have been found in 1-amino-1-ethinylcyclopropane [257], 2-cyclopropylideneethanol [258], 2-furan-methanethiol [259], 2-furanemethanol [260] and other similar compounds. A weak H-bond has been also observed in cyclopropane-methanethiol between the H atom of the thiol group and the ''quasi-p'' electrons of the cyclopropyl ring, able to act as proton acceptors [261].…”