Conformation and crystal structures of 1-amino­cyclo­hexa­neacetic acid (β(3,3)Ac(6)c) in N-protected derivatives

N-Protected derivatives of 1-amino­cyclo­hexa­neacetic acid (β(3,3)-Ac(6)c), namely Valeroyl-β(3,3)-Ac(6)c-OH [2-(1-pentanamidocyclohexyl)acetic acid, C(13)H(23)NO(3)], (I), Fmoc-β(3,3)-Ac(6)c-OH [2-(1-{[(9H-fluoren-9-yloxy)carbonyl]amino}cyclohexyl)acetic acid, C(23)H(25)NO(4)], (II), and Pyr-β(3,3)-Ac(6)c-OH {2-[1-(pyrazine-2-amido)cyclohexyl]acetic acid, C(13)H(17)N(3)O(3)}, (III), were synthesized and their conformational properties were determined by X-ray diffraction analysis. The backbone torsion angles (ϕ, θ) for β(3,3)-Ac(6)c-OH are restricted to gauche conformations in all the derivatives, with a chair conformation of the cyclo­hexane ring. In the crystal structure of (I), the packing of mol­ecules shows both carb­oxy­lic acid R (2) (2)(8) O—H⋯O and centrosymmetric R (2) (2)(14) N—H⋯O hydrogen-bonding inter­actions, giving rise to chains along the c-axis direction. In (II), centrosymmetric carb­oxy­lic acid R (2) (2)(8) O—H⋯O dimers are extended through N—H⋯O hydrogen bonds and together with inter-ring π–π inter­actions between Fmoc groups [ring centroid distance = 3.786 (2) Å], generate a layered structure lying parallel to (010). In the case of compound (III), carb­oxy­lic acid O—H⋯N(pyrazine) hydrogen bonds give rise to zigzag ribbon structures extending along the c-axis direction.