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The mol­ecule of the title compound, C16H30O2, features a trans-fused bicyclic system. The six-membered ring has a chair conformation. The mol­ecules are linked via an O—H⋯O hydrogen bond [O⋯O = 2.7696 (11) Å and O—H⋯O = 174.2 (13)°] to form chains along the b axis. An intra­molecular O—H⋯O hydrogen bond [O⋯O = 2.6722 (11) Å and O—H⋯O = 148.4 (13)°] is present. [ABSTRACT FROM AUTHOR]

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 C atom adjacent to the quaternary C atom being the flap, and the methyl and isopropyl substituents lying to the same side of the ring. The dihedral angles between the four nearly coplanar atoms of the five-membered ring and the flap and the aromatic ring are 35.74 (15) and 55.72 (9)°, respectively. The bond angles around the S atom are in the range from 103.26 (12) to 120.65 (14)°. In the crystal, mol-ecules are linked via N-H⋯O hydrogen bonds, forming a chain along the a axis.

The title hydrate, C17H28O2·H2O, was synthesized in order to determine the relative configuration of the tetra-cyclic framework. The fused 5,6,7-tricarbocyclic core exhibits an entire cis-annulation, featuring a 1,4-cis-relation of the angular methyl groups in the six-membered ring. The oxa bridge of the ep-oxy-cyclo-heptane moiety is oriented towards the concave face of the boat-shaped mol-ecule, whereas the angular methyl groups are directed towards the convex face. The asymmetric unit of the crystal contains two nearly identical formula units, which are related via a pseudo-centre of symmetry. The structure could be solved in the space groups I-4 and I41/a. The refinement in the acentric space group, however, gave significantly better results and these are used in this paper. O-H⋯O hydrogen bonds are observed between the organic mol-ecules, between the organic mol-ecules and the water mol-ecules, and between the water mol-ecules, forming a chain along the c-axis direction.

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 aromatic ring are 38.8 (4) and 22.9 (2)°, respectively. The bond angles around the S atom are in the range 104.11 (16)-119.95 (16)°. In the crystal, mol-ecules are linked via N-H⋯O by hydrogen bonds, forming a chain along the a-axis direction.

In the title compound, C(21)H(18)Si, the coordination geometry around the Si atom is a slightly distorted tetra-hedron with C-Si-C angles in the range 106.05 (11) to 110.58 (10) ° and Si-C bond lengths in the range 1.855 (2) to 1.883 (3) Å. The alkyne C-C bond length is 1.167 (4) Å. The dihedral angles between the three phenyl rings are 63.89 (7), 86.38 (7) and 70.51 (8)°. In the crystal, mol-ecules inter-act only by van der Waals forces.

The title compound, C(19)H(24)ClNO(5), was synthesized and subsequently employed in an Evans alkyl-ation. The purpose was to prove the absolute configuration in the projected synthesis of the side chain of (-)-Lytophilippine A. The oxazolidinone and the isopropylidene acetal rings have twisted conformations. The oxazolidinone and side-chain carbonyl groups are orientated in an anti-periplanar arrangement to minimize van der Waals repulsions. Furthermore, the Cl atom and the acetonide-protected secondary alcohol are also in an anti-periplanar arrangement with a torsion angle of 173.64 (14)°. The absolute configuration was determined and agrees with the configuration of the used chiral auxiliary.

The title compound, C(12)H(18)N(4)O(2)SSi, was synthesized to be employed in a Julia-Kocieński olefination. In the mol-ecule, the dihedral angle between the phenyl ring and the tetra-zole ring is 41.50 (5)°. The significantly longer Si-C(methyl-ene) bond [1.8786 (13) Å] and the shortened adjacent C-C bond [1.5172 (18) Å], as well as the significant deviation of the corresponding Si-C-C angle [114.16 (9)°] from the ideal tetra-hedral angle, can be attributed to the β-effect of silicon. In the crystal, mol-ecules are held together by van der Waals inter-actions.

In the title compound, [Cu(C(15)H(26)N(2)O(2))(C(3)H(7)NO)(2)][SbF(6)](2), which is a potential catalyst in the catalytic asymmetric Gosteli-Claisen rearrangement, the central Cu(II) atom is in a nearly square-planar cis-N(2)O(2) environment in the cation arising from its coordination by an N,N-bidentate 2,2-bis-[(4S)-4-isopropyl-4,5-dihydro-1,3-oxazol-2-yl]propane ligand and two O-bonded N,N-dimethyl-formamide mol-ecules. Two SbF(6) (-) anions are positioned on opposite sides of the plane through the CuN(2)O(2) unit, generating an axially distorted CuN(2)O(2)F(2) octa-hedral geometry for the metal ion.

The relative configuration of the title compound, C(19)H(28)O(3)Si, which was synthesized using a dienolate-[2,3]-Wittig rearrangement, was corroborated by single-crystal X-ray diffraction analysis. The Si-C bond distances are in the range 1.858 (2)-1.880 (2) Å and an intra-molecular O-H⋯O hydrogen bond helps to stabilize the mol-ecular conformation.

The relative configuration of the title compound, C(11)H(18)O(3), which was synthesized using a catalytic asymmetric Gosteli-Claisen rearrangement, a diastereoselective reduction with K-Selectride and an Evans aldol addition, was corroborated by single-crystal X-ray diffraction analysis. The five-membered ring has an envelope conformation with a dihedral angle of 29.46 (16)° between the coplanar part and the flap (the hydr-oxy-bearing ring C atom). In the crystal, mol-ecules are connected via bifurcated O-H⋯(O,O) hydrogen bonds, generating [010] chains.

An intra-molecular Claisen-like cyclization of ethyl 2-acet-oxy-4,4-dimethyl-1-(3-methyl-but-2-en-yl)cyclo-hex-2-enecarboxylate followed by dialkyl-ation yielded the bicyclic title compound, C(23)H(26)O(4). In both of the fused six-membered rings exist fragments of four atoms which are planar, whereas the remaining two atoms deviate by up to 0.682 (3) Å on one side of the plane of the ring containing an O atom and by up to 0.415 (3) Å on opposite sides of the other ring. The dihedral anglebetween the planar fragments of the six-membered rings is 41.76 (10)°

The title compound, C(26)H(38)O(3), was prepared by an intra-molecular Claisen-like cyclization of ethyl 2-acet-oxy-4,4-dimethyl-1-(3-methyl-but-2-en-yl)cyclo-hex-2-enecarboxyl-ate followed by dialkyl-ation. One of the methyl groups is disordered over two sets of sites in a 0.67:0.33 ratio.

The title compound, C(16)H(18)F(6)O(4), was obtained through an unprecedented one-pot reaction sequence involving a Gosteli-Claisen rearrangement and a cyclo-isomerization. The constitution and relative configuration were determined by single-crystal X-ray diffraction analysis. In the crystal, mol-ecules are connected via O-H ⋯ O hydrogen bonds.

In the title compound, [Cu(C(17)H(30)N(2)O(2))(C(3)H(7)NO)(2)][SbF(6)](2), which is a potential catalyst in the asymmetric Gosteli-Claisen rearrangement, the Cu atom adopts a distorted cis-CuN(2)O(2) square-planar geometry arising from N,N'-bidentate coordin-ation by the chiral ligand and two O-bonded dimethyl-formamide mol-ecules. Two short C-H⋯O contacts occur within the ligand and two weak inter-molecular C-H⋯F bonds may help to establish the packing.

The relative configuration of the title compound, C(11)H(18)O(3), was corroborated by single-crystal X-ray diffraction analysis. In the crystal, mol-ecules are linked via a O-H⋯O hydrogen bond and a chain of mol-ecules is formed along [010].

The title compound, C(11)H(18)O(3), was synthesized to prove the relative configuration of the corresponding acyclic C1-C8 stereopentade. It crystallizes with two mol-ecules in the asymmetric unit, which show only slight differences. The mol-ecules are linked via O-H⋯O hydrogen bonds, resulting in two crystallographically independent chains of mol-ecules propagating in the a-axis direction. The absolute configuration was known from the synthesis.

The chiral title compound, C(22)H(35)NO(5)SSi, is a precursor of novel furan-omycin derivatives. It crystallizes with two molecules in the asymmetric unit; these show different conformations of the silyl substitutent, as indicated by the Si-O-C-C torsion angles of 41.4 (7) and -84.5 (5)° in the two mol-ecules. The anti configuration of the adjacent stereogenic centers is consistent with the Felkin-Anh model. Each of the two crystallographically independent mol-ecules is connected with a neighbouring mol-ecule of the same type via two symmetry-equivalent O-H⋯O hydrogen bonds.

The title compound, C(6)H(9)NO(4), was prepared stereoselectively as a precursor for 1-aza-dienes in a study of hetero-Diels-Alder reactions. The configuration of the C=N double bond was found to be Z, corroborating earlier assignments of similar compounds based only on NMR and IR spectroscopic analysis.

An oxonium ion with hydroxymethyl and methylidene substituents is found in the salts 1-MF 6 (M=As, Sb), which can be isolated from solutions of formaldehyde in superacids HF/MF 5 . Their formation was at first surprising, since NMR spectroscopy indicates that protonated monofluoromethanol is present in solution., (© 1998 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.)