The title compound, C17H24N2O3S, was synthesized in order to determine the relative configuration of the corresponding β-keto aldehyde. In the U-shaped mol-ecule, the five-membered ring approximates an envelope with the methyl-ene atom adjacent to the quaternary C atom being the flap. The dihedral angles between the four nearly coplanar atoms of the five-membered ring and the flap and the aroma...

PURPOSE The aim of this pilot study was to evaluate the success rate of a chairside ridge augmentation procedure using bone autografts harvested with trephine drills and placed without the use of screws. METHODS Thirty patients were recruited for the study. After the surgical site was anesthetized and a crestal incision was made, an envelope flap was retracted using blunt dissection limited t...

The title compound, C(6)H(11)NO(3)S, crystallizes utilizing a three-dimensional set of O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds. The 1,3-oxazolidin-2-one ring adopts an envelope conformation with the C atom bearing the hy-droxy-methyl group as the flap.

The absolute structure of the title compound, C(11)H(13)FN(+)·Cl(-), has been determined. The five-membered ring has an envelope conformation with the N atom at the flap position. In the crystal structure, the Cl(-) anion links with the organic cation via N-H⋯Cl hydrogen bonding.

In the title compound, C25H29FO4, each cyclo-hexenone ring has an envelope conformation with the dimethyl-substituted atom as the flap. The hy-droxy and carbonyl groups form two intra-molecular O-H⋯O hydrogen bonds, as is typical for xanthene derivatives. In the crystal, very weak C-H⋯O hydrogen bonds link mol-ecules into dimers.

In the title compound, C14H14O4, the dihedral angle between the hydro-furan and benzene rings is 88.41 (15)°. The hydro-pyran ring adopts an envelope conformation, with the O-bound methyl-ene C atom as the flap. In the crystal, weak aromatic π-π stacking is observed [centroid-centroid separation = 3.848 (2) Å].

In the title compound, C(20)H(29)NO(8)S, the two five-membered rings adopt envelope conformations (with an O atom at the flap in each case), while the six-membered pyran ring displays a twist-boat conformation. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds into a supra-molecular chain running along the a axis.

In the title compound, C(11)H(19)Cl(2)NO(2), the oxazolidine ring is in an envelope conformation with the O atom forming the flap. In the crystal structure, mol-ecules are linked by weak inter-molecular C-H⋯O hydrogen bonds, forming chains.

The piperidine ring in the title compound, C24H25NO3, adopts an envelope conformation with the N atom being the flap atom, and each C=C double bond exhibits an E conformation. In the crystal, C-H⋯O hydrogen bonds link the mol-ecules, forming supramolecular layers that stack along the a axis.

In the crystal structure of the title compound, C(19)H(17)Cl(2)NO, the indoline and benzopyran ring systems are approximately perpendicular to each other. The indoline ring is in an envelope conformation with the spiro C atom as the flap. The N atom of the indoline ring forms a pyramidal environment, the sum of the angles at this atom being 352.46°.