26853-51-0Relevant articles and documents
Lipase-catalyzed kinetic resolution of 2-aminocyclopentane- and 2-aminocyclohexanecarboxamides
Fitz, Monika,Lundell, Katri,Fueloep, Ferenc,Kanerva, Liisa T.
, p. 1129 - 1134 (2007/10/03)
Candida antarctica lipase B (CAL-B)-catalyzed N-acylation with 2,2,2-trifluoroethyl butanoate in solvent mixtures of tert-butyl methyl ether and tert-amyl alcohol was used to prepare all the enantiomers of cis- and trans-2-aminocyclopentane- and -cyclohexanecarboxamides. An unexpected change in enantiopreference, accompanied by low enantioselectivity, was observed when Pseudomonas cepacia lipase (cis-cyclohexane substrate) or C. antarctica lipase A (cis-cyclopentane and -cyclohexane substrates) replaced CAL-B.
EXPERIMENTAL STUDIES OF THE ANOMERIC EFFECT. PART 2 RING INVERSION AND NITROGEN INVERSION EQUILIBRIA IN CIS-DECAHYDROQUINAZOLINES
Booth, Harold,Khedhair, Khedhair A.,Al-Shirayda, Hatif A. R. Y.
, p. 1465 - 1476 (2007/10/02)
The positions of conformational equilibria due to the double ring inversion in cis-decahydroquinazoline (7-->//07-->8 1.08 kcal mol-1; -ΔG09-->10 1.10 kcal mol-1) for the conformation which would allow the lone pairs on N(1) and N(3) to lie on the hindered 'inside' face of the molecules.However, the values of 3J(CHNH) coupling constants for both cis-decahydro-3-methylquinazoline (10) and cis (4aH, 8aH) cis (2H, 8aH)-decahydro-2,3-dimethylquinazoline (14) show that the N-inversion equilibrium at N(1) prefers the conformation in which N(1)-H is 'inside' (axial), and N(1)-lone pair equatorial, thus demonstrating the ability of the anomeric effect to outweigh steric repulsions.
