rac-(1S*,4aS*,8aS*)-4a-Hydroxy-2-methylperhydrospiro[isoquinoline-4,1′-cyclohexan]-2′-one

Abstract

In the title compound, C15H25NO2, all three six-membered rings adopt chair conformations. The cyclo­hexane and piperidine rings within the perhydro­isoquinoline are trans–trans fused. The N atom has a trigonal–pyramidal geometry (the sum of the bond angles is 328.0°). The methyl substituent occupies the sterically preferrable equatorial position. In the crystal, mol­ecules form infinite [100] chains via O—H⋯N hydrogen bonds.

Uncommon expansion of piperidine ring into hydroazocine ring in reactions of some piperidine β-acyl derivatives with acetylenecarboxylic acids esters

“…This zwitter ion then suffers an intramolecular decyclization of retroaldol type which may be accompanied with the tautomeric enolization and the formation of a linear adduct C (Scheme 2). Similar 1,3-zwitter ions containing in their structure an allylamine fragment may undergo an intramolecular [1,3]-sigmatropic rearrangement (through a fourmembered transition state [14]) with the cleavage of the N-С sp3 bond and the insertion of the residue of maleic acid ester. The possibility of such processes was mentioned in [9,10].…”

“…Initial 4-hydroxy-1-methyl-4-phenylpiperidin-3-yl (phenyl)methanone 3 was obtained from commercial (Aldrich) acetophenone by procedure [5]. Molecular structure of compound 1 was proved by XRD analysis [1]. All calculations were carried out using SHELXTL software [18].…”

“…In a preliminary communication [1] we reported shortly on the formation of spiro compound 1 at the condensation of cyclohexanone with formaldehyde and methylamine. This cascade reaction proceeds similarly to α-tetralone condensation through Mannich base A [2][3][4] that further undergoes cyclization into γ-piperidol derivative due to an intramolecular condensation of aldol type [5,6] (Scheme 1).…”