Novel Liquid Crystalline Compounds Containing Bicyclo[3.1.0]hexane Core Units

Abstract

Keywords:Cross-coupling / Cycloadditions / Liquid crystals / Small ring systems / Structure elucidation Additions of ethyl or tert-butyl diazoacetates to 4-substituted cyclopentenes 6 and 17 under dirhodium tetraacetate/tetraoctanoate catalysis led to mixtures of tert-butyl endo, exoand exo,exo-3-carboxyl(aryl)bicyclo[3.1.0]hexane-6-carboxylates 7 and 18 in yields of 54−90% from which exo,exodiastereomers were isolated in yields of 39−63%. Diester exo,exo-7 was saponified and converted into diaryl diesters exo,exo-9a,b in overall yields of 42 and 46%, respectively. The esters exo,exo-18 were reduced to the corresponding hydroxymethyl derivatives, these were transformed to the iodomethyl compounds which in turn were coupled with various alkylmagnesium halides, via Li 2 CuCl 4 catalysis, to give 3-aryl-6-alkylbicyclo[3.1.0]hexyl derivatives exo,exo-21 in overall yields of 72−83%. Fluorinated 3-(2-arylethyl)-6-pentylbicyclo[3.1.0]hexane exo,exo-32 could be prepared in five steps from 4-ethoxy-2,3-difluorobenzaldehyde 26a ad-

Facile Access to Bicyclic Sultams with Methyl 1‐Sulfonylcyclopropane‐1‐carboxylate Moieties

“…In the crystal, the 2-thia-3-azabicyclo[3.1.0]hexane skeleton adopts a flattened boat conformation, as is frequently observed for bicyclo[3.1.0]-hexane derivatives. [4] The interplanar angle between the three-and five-membered rings is 110.4°, and the nitrogen corner of the five-membered ring is bent by an angle of 34.3°towards the three-membered ring. The C=C bond distal to the two electron-withdrawing groups is shorter [147.5(2) pm] than the two proximal bonds [152.0(2) and 152.6(2) pm], a typical effect caused by electron-withdrawing substituents on a cyclopropane ring.…”

1-[4-(Iodomethyl)cyclohexyl]-4-methylbenzene

“…For background to liquid crystals, see: Demus & Hauser (1990). For the synthesis, see: Kozhushkov et al (2004). Data collection: CrystalClear (Rigaku/MSC, 2005); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: CrystalStructure (Rigaku/MSC, 2005).…”

Two Distinct Conformations of GABA Locked by Embedding in the Bicyclo[3.1.0]hexane Core Structure

“…Hence, irrespective of the presence of heteroatoms in the five-membered ring and also largely independent of the substitution pattern, a saturated bicyclo[3.1.0] core unit preferentially adopts a boatshaped conformation. [20] The predominance of boat-shaped conformations can be rationalized in terms of almost perfectly staggered arrangements along the two single bonds of the five-membered ring adjacent to the bridgehead positions ( Figure 2 e), whereas the chair-type conformation would result in energetically less favored eclipsed arrangements (Figure 2 d). For the compounds with chair-like conformations, a prominent pattern is a syn--endo disubstitution at C3 and C6 that would lead to severe steric congestion in a boat-type conformation.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12] They have been used as conformationally locked analogues of nucleoside building blocks [9][10][11][12] and as intrinsically interesting building blocks in numerous other applications. [13][14][15][16] They have been reported as intermediates in natural compound synthesis, [17] or as constituents of bioactive compounds, [18,19] novel materials, [20] and catalysts. [21] Methanoproline 1, a naturally occurring inhibitor of proline metabolism, [1] and 3-azabicyclo[3.1.0]hex-6-ylamine 2, a constituent of the potent broad-spectrum antibiotic trovafloxacin, [2] are particularly prominent examples.…”