organic compounds
(1R,3S,8R)-3,7,7,10-Tetramethyltricyclo[6.4.0.01,3]dodec-9-en-11-one
aLaboratoire de Physico-Chimie Moléculaire et Synthése Organique, Département de Chimie, Faculté des Sciences, Semlalia BP 2390, Marrakech 40001, Morocco, and bLaboratoire de Chimie de Coordination, 205 route de Narbonne, 31077 Toulouse Cedex 04, France
*Correspondence e-mail: a.auhmani@uca.ma
The 16H24O, has been deduced from the chemical pathway. The six-membered ring has a roughly half-chair conformation with the quaternary C atom as the flap. The seven-membered ring displays a chair conformation. In the crystal, there is a weak C—H⋯O hydrogen bond between the methylene group of the cyclopropane ring and the carbonyl group of a screw-axis-related molecule, which builds up a zigzag-like chain along the b-axis direction.
of the title compound, CCCDC reference: 977683
Related literature
For related structures, see: Benharref et al. (2012); Gassman & Gorman (1990); Lassaba et al. (1997). For ring puckering analysis, see: Cremer & Pople (1975). For structural discussion, see: Evans & Boeyens (1989); Spek (2009). For chemical properties, see: Auhmani et al. (2002); Danyang et al. (2007); Tetsuhiro et al. (2003).
Experimental
Crystal data
|
Data collection: APEX2 (Bruker, 2012); cell SAINT (Bruker, 2012); data reduction: SAINT; program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2008b); molecular graphics: ORTEPIII (Burnett & Johnson, 1996), ORTEP-3 for Windows (Farrugia, 2012) and Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXL2013.
Supporting information
CCDC reference: 977683
https://doi.org/10.1107/S1600536813034041/fy2107sup1.cif
contains datablocks I, New_Global_Publ_Block. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536813034041/fy2107Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S1600536813034041/fy2107Isup3.cml
To a cooled (0°C) solution of (1S,3S,8R)-3,7,7,10-tetramethyl tricyclo[6.4.0.01,3]dodec-9-ene 2 (4.6 mmol) in 50 ml of a solvent mixture THF/H2O (4/1, v/v), NBS (9.16 mmol) was added in small portions. The mixture was kept under stirring at 0°C for two hours. After completion of the reaction, 15% sodium hydrogenocarbonate solution was added and the reaction mixture was taken up in ether, dried over anhydrous sodium sulfate, and evaporated. The crude product was purified by silica gel
(230–400 mesh) using hexane/ethyl acetate (95:5) as to give (1R,3S,8R)-3,7,7,10-tetramethyltricyclo[6.4.0.01.3]dodec-9-en-11-one, 1 (2.85 mmol) in 62% yield. X-ray quality crystals were obtained by slow solvent evaporation from an isohexane solution of the title compound.All H atoms attached to C atoms were fixed geometrically and treated as riding with C—H = 0.99 Å (methylene), 0.98 Å (methyl), 0.95 Å (methine) with Uiso(H) = 1.2Ueq(CH and CH2) or Uiso(H) = 1.5Ueq(CH3).
In the absence of significant
the could not be reliably determined and any references to the were removed.The 0 0 1 reflection appears affected by the beam stop and it has been removed.
α,β-unsaturated are versatile intermediates in organic synthesis, since they are important precursors in the synthesis of enaminones (Auhmani et al., 2002), prodrugs (Danyang et al., 2007) and natural compounds (Tetsuhiro et al., 2003).
With the aim of preparing a new α,β-unsaturated ketone with sesquiterpenic skeleton, we report here the synthesis of (1R,3S,8R)-3,7,7,10-tetramethyltricyclo[6.4.0.01.3]dodec-9-en-11-one, 1. (1S,3S,8R)-3,7,7,10-tetramethyltricyclo[6.4.0.01,3]dodec-9-ene, 2, was treated with N-bromosuccinimide (NBS). The reaction was conducted at 0°C to provide the α,β-unsaturated ketone 1 as colorless crystals in 62% yield. Its structure was characterized by its mass and NMR spectroscopic data. Furthermore, an X-ray single-crystal structure analysis allowed its complete identification as (1R,3S,8R)-3,7,7,10-tetramethyltricyclo[6.4.0.01.3]dodec-9-en-11-one.
A view of the molecule is represented in Fig. 1. As observed in related compounds (Gassman & Gorman, 1990; Lassaba et al., 1997; Benharref et al., 2012), each molecule is built up from two fused six-and seven-membered rings. The six-membered ring has roughly half-chair conformation with the puckering parameters: Q = 0.4166 (11) Å, spherical polar angle θ = 124.02 (15)° and φ = 170.57 (19)° (Spek, 2009; Cremer & Pople, 1975), whereas the seven-membered ring displays a chair conformation with a total puckering amplitude of 0.7919 (11) Å (Evans & Boeyens, 1989).
There is a weak C—H···O hydrogen bond, which builds up a zigzag-like chain developing along the b axis (Table 1, Fig. 2)
For related structures, see: Benharref et al. (2012); Gassman & Gorman (1990); Lassaba et al. (1997). For structural discussion, see: Cremer & Pople (1975); Evans & Boeyens (1989); Spek (2009). For chemical properties, see: Auhmani et al. (2002); Danyang et al. (2007); Tetsuhiro et al. (2003).
Data collection: APEX2 (Bruker, 2012); cell
SAINT (Bruker, 2012); data reduction: SAINT (Bruker, 2012); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2008b); molecular graphics: ORTEPIII (Burnett & Johnson, 1996), ORTEP-3 for Windows (Farrugia, 2012) and Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXL2013 (Sheldrick, 2008b).C16H24O | F(000) = 256 |
Mr = 232.35 | Dx = 1.134 Mg m−3 |
Monoclinic, P21 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2yb | Cell parameters from 7217 reflections |
a = 6.4379 (2) Å | θ = 3.0–33.0° |
b = 7.8889 (3) Å | µ = 0.07 mm−1 |
c = 13.5122 (5) Å | T = 180 K |
β = 97.430 (2)° | Plate, colourless |
V = 680.49 (4) Å3 | 0.38 × 0.23 × 0.08 mm |
Z = 2 |
Bruker APEXII CCD diffractometer | 4902 independent reflections |
Radiation source: sealed tube | 4331 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.030 |
φ and ω scans | θmax = 33.2°, θmin = 3.0° |
Absorption correction: multi-scan (SADABS; Sheldrick, 2008a) | h = −9→9 |
Tmin = 0.661, Tmax = 0.747 | k = −12→12 |
15568 measured reflections | l = −20→20 |
Refinement on F2 | 1 restraint |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.041 | H-atom parameters constrained |
wR(F2) = 0.111 | w = 1/[σ2(Fo2) + (0.0667P)2 + 0.0218P] where P = (Fo2 + 2Fc2)/3 |
S = 1.04 | (Δ/σ)max = 0.001 |
4902 reflections | Δρmax = 0.30 e Å−3 |
158 parameters | Δρmin = −0.18 e Å−3 |
C16H24O | V = 680.49 (4) Å3 |
Mr = 232.35 | Z = 2 |
Monoclinic, P21 | Mo Kα radiation |
a = 6.4379 (2) Å | µ = 0.07 mm−1 |
b = 7.8889 (3) Å | T = 180 K |
c = 13.5122 (5) Å | 0.38 × 0.23 × 0.08 mm |
β = 97.430 (2)° |
Bruker APEXII CCD diffractometer | 4902 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2008a) | 4331 reflections with I > 2σ(I) |
Tmin = 0.661, Tmax = 0.747 | Rint = 0.030 |
15568 measured reflections |
R[F2 > 2σ(F2)] = 0.041 | 1 restraint |
wR(F2) = 0.111 | H-atom parameters constrained |
S = 1.04 | Δρmax = 0.30 e Å−3 |
4902 reflections | Δρmin = −0.18 e Å−3 |
158 parameters |
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. |
x | y | z | Uiso*/Ueq | ||
C1 | 0.31651 (18) | 0.79421 (18) | 0.28074 (9) | 0.0192 (2) | |
C2 | 0.2552 (2) | 0.98024 (19) | 0.27484 (11) | 0.0255 (3) | |
H2A | 0.1104 | 1.0088 | 0.2457 | 0.031* | |
H2B | 0.3159 | 1.0555 | 0.3297 | 0.031* | |
C3 | 0.40116 (18) | 0.91018 (18) | 0.20572 (9) | 0.0213 (3) | |
C4 | 0.3155 (2) | 0.8894 (2) | 0.09629 (10) | 0.0261 (3) | |
H4A | 0.3706 | 0.9821 | 0.0577 | 0.031* | |
H4B | 0.1611 | 0.9005 | 0.0888 | 0.031* | |
C5 | 0.3716 (2) | 0.7200 (2) | 0.05222 (11) | 0.0318 (3) | |
H5A | 0.5148 | 0.6876 | 0.0819 | 0.038* | |
H5B | 0.3727 | 0.7338 | −0.0205 | 0.038* | |
C6 | 0.2204 (3) | 0.5769 (2) | 0.07006 (11) | 0.0322 (3) | |
H6A | 0.2565 | 0.4778 | 0.0308 | 0.039* | |
H6B | 0.0780 | 0.6135 | 0.0417 | 0.039* | |
C7 | 0.2086 (2) | 0.51533 (19) | 0.17792 (10) | 0.0244 (3) | |
C8 | 0.14660 (17) | 0.66525 (17) | 0.24508 (9) | 0.0191 (2) | |
H8 | 0.0359 | 0.7304 | 0.2023 | 0.023* | |
C9 | 0.04465 (19) | 0.60496 (19) | 0.33343 (10) | 0.0236 (3) | |
H9 | −0.0870 | 0.5499 | 0.3191 | 0.028* | |
C10 | 0.1211 (2) | 0.6213 (2) | 0.42964 (11) | 0.0263 (3) | |
C11 | 0.3324 (2) | 0.6937 (2) | 0.45837 (10) | 0.0271 (3) | |
C12 | 0.4560 (2) | 0.7448 (2) | 0.37599 (10) | 0.0263 (3) | |
H12A | 0.5471 | 0.6493 | 0.3614 | 0.032* | |
H12B | 0.5474 | 0.8418 | 0.3988 | 0.032* | |
C13 | 0.6305 (2) | 0.9621 (2) | 0.22205 (12) | 0.0310 (3) | |
H13A | 0.6697 | 0.9941 | 0.2921 | 0.047* | |
H13B | 0.6521 | 1.0589 | 0.1791 | 0.047* | |
H13C | 0.7175 | 0.8669 | 0.2056 | 0.047* | |
C14 | 0.4145 (2) | 0.4307 (2) | 0.22037 (13) | 0.0352 (4) | |
H14A | 0.4383 | 0.3308 | 0.1802 | 0.053* | |
H14B | 0.4072 | 0.3960 | 0.2895 | 0.053* | |
H14C | 0.5301 | 0.5110 | 0.2186 | 0.053* | |
C15 | 0.0350 (3) | 0.3801 (2) | 0.16921 (14) | 0.0372 (4) | |
H15A | 0.0327 | 0.3251 | 0.2341 | 0.056* | |
H15B | 0.0626 | 0.2950 | 0.1197 | 0.056* | |
H15C | −0.1007 | 0.4339 | 0.1483 | 0.056* | |
C16 | 0.0016 (3) | 0.5678 (3) | 0.51319 (14) | 0.0403 (4) | |
H16A | −0.1322 | 0.5173 | 0.4852 | 0.060* | |
H16B | −0.0246 | 0.6670 | 0.5534 | 0.060* | |
H16C | 0.0839 | 0.4843 | 0.5553 | 0.060* | |
O1 | 0.4059 (2) | 0.7093 (2) | 0.54568 (8) | 0.0492 (4) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0190 (4) | 0.0222 (6) | 0.0168 (5) | −0.0001 (4) | 0.0033 (4) | 0.0009 (4) |
C2 | 0.0287 (6) | 0.0230 (7) | 0.0263 (6) | 0.0003 (5) | 0.0095 (5) | −0.0021 (5) |
C3 | 0.0214 (5) | 0.0230 (7) | 0.0202 (6) | 0.0001 (4) | 0.0055 (4) | 0.0023 (5) |
C4 | 0.0300 (6) | 0.0289 (7) | 0.0199 (6) | 0.0033 (5) | 0.0047 (4) | 0.0061 (5) |
C5 | 0.0407 (7) | 0.0376 (9) | 0.0189 (6) | 0.0035 (6) | 0.0100 (5) | −0.0003 (6) |
C6 | 0.0446 (7) | 0.0312 (8) | 0.0208 (7) | 0.0009 (6) | 0.0043 (5) | −0.0060 (6) |
C7 | 0.0277 (5) | 0.0225 (7) | 0.0227 (6) | 0.0030 (5) | 0.0019 (4) | −0.0019 (5) |
C8 | 0.0175 (4) | 0.0214 (6) | 0.0181 (5) | 0.0022 (4) | 0.0015 (4) | 0.0013 (5) |
C9 | 0.0205 (5) | 0.0246 (7) | 0.0263 (6) | 0.0004 (5) | 0.0057 (4) | 0.0040 (5) |
C10 | 0.0284 (6) | 0.0277 (7) | 0.0242 (6) | 0.0020 (5) | 0.0082 (5) | 0.0070 (5) |
C11 | 0.0308 (6) | 0.0311 (8) | 0.0190 (6) | 0.0015 (5) | 0.0019 (4) | 0.0064 (5) |
C12 | 0.0225 (5) | 0.0371 (8) | 0.0185 (6) | −0.0035 (5) | 0.0000 (4) | 0.0033 (5) |
C13 | 0.0240 (5) | 0.0370 (9) | 0.0326 (7) | −0.0047 (5) | 0.0061 (5) | 0.0056 (6) |
C14 | 0.0369 (7) | 0.0299 (8) | 0.0390 (8) | 0.0146 (6) | 0.0056 (6) | −0.0002 (6) |
C15 | 0.0438 (8) | 0.0276 (8) | 0.0393 (8) | −0.0068 (6) | 0.0020 (6) | −0.0064 (7) |
C16 | 0.0423 (7) | 0.0500 (11) | 0.0312 (8) | −0.0022 (7) | 0.0150 (6) | 0.0136 (7) |
O1 | 0.0509 (6) | 0.0765 (11) | 0.0185 (5) | −0.0110 (7) | −0.0021 (4) | 0.0070 (6) |
C1—C3 | 1.5181 (18) | C8—H8 | 1.0000 |
C1—C2 | 1.519 (2) | C9—C10 | 1.336 (2) |
C1—C12 | 1.5220 (18) | C9—H9 | 0.9500 |
C1—C8 | 1.5255 (18) | C10—C11 | 1.4796 (19) |
C2—C3 | 1.5123 (17) | C10—C16 | 1.5065 (19) |
C2—H2A | 0.9900 | C11—O1 | 1.2192 (17) |
C2—H2B | 0.9900 | C11—C12 | 1.5048 (18) |
C3—C4 | 1.5186 (19) | C12—H12A | 0.9900 |
C3—C13 | 1.5207 (17) | C12—H12B | 0.9900 |
C4—C5 | 1.525 (2) | C13—H13A | 0.9800 |
C4—H4A | 0.9900 | C13—H13B | 0.9800 |
C4—H4B | 0.9900 | C13—H13C | 0.9800 |
C5—C6 | 1.530 (2) | C14—H14A | 0.9800 |
C5—H5A | 0.9900 | C14—H14B | 0.9800 |
C5—H5B | 0.9900 | C14—H14C | 0.9800 |
C6—C7 | 1.548 (2) | C15—H15A | 0.9800 |
C6—H6A | 0.9900 | C15—H15B | 0.9800 |
C6—H6B | 0.9900 | C15—H15C | 0.9800 |
C7—C14 | 1.528 (2) | C16—H16A | 0.9800 |
C7—C15 | 1.538 (2) | C16—H16B | 0.9800 |
C7—C8 | 1.5733 (18) | C16—H16C | 0.9800 |
C8—C9 | 1.5115 (17) | ||
C3—C1—C2 | 59.73 (9) | C1—C8—C7 | 117.29 (9) |
C3—C1—C12 | 119.71 (10) | C9—C8—H8 | 105.6 |
C2—C1—C12 | 114.38 (12) | C1—C8—H8 | 105.6 |
C3—C1—C8 | 119.72 (11) | C7—C8—H8 | 105.6 |
C2—C1—C8 | 117.19 (10) | C10—C9—C8 | 126.53 (12) |
C12—C1—C8 | 114.63 (11) | C10—C9—H9 | 116.7 |
C3—C2—C1 | 60.10 (9) | C8—C9—H9 | 116.7 |
C3—C2—H2A | 117.8 | C9—C10—C11 | 120.23 (11) |
C1—C2—H2A | 117.8 | C9—C10—C16 | 122.86 (13) |
C3—C2—H2B | 117.8 | C11—C10—C16 | 116.91 (14) |
C1—C2—H2B | 117.8 | O1—C11—C10 | 121.43 (13) |
H2A—C2—H2B | 114.9 | O1—C11—C12 | 120.82 (13) |
C2—C3—C1 | 60.17 (9) | C10—C11—C12 | 117.73 (12) |
C2—C3—C4 | 117.69 (11) | C11—C12—C1 | 112.55 (10) |
C1—C3—C4 | 117.95 (11) | C11—C12—H12A | 109.1 |
C2—C3—C13 | 118.74 (12) | C1—C12—H12A | 109.1 |
C1—C3—C13 | 119.42 (11) | C11—C12—H12B | 109.1 |
C4—C3—C13 | 113.19 (11) | C1—C12—H12B | 109.1 |
C3—C4—C5 | 113.60 (12) | H12A—C12—H12B | 107.8 |
C3—C4—H4A | 108.8 | C3—C13—H13A | 109.5 |
C5—C4—H4A | 108.8 | C3—C13—H13B | 109.5 |
C3—C4—H4B | 108.8 | H13A—C13—H13B | 109.5 |
C5—C4—H4B | 108.8 | C3—C13—H13C | 109.5 |
H4A—C4—H4B | 107.7 | H13A—C13—H13C | 109.5 |
C4—C5—C6 | 113.40 (11) | H13B—C13—H13C | 109.5 |
C4—C5—H5A | 108.9 | C7—C14—H14A | 109.5 |
C6—C5—H5A | 108.9 | C7—C14—H14B | 109.5 |
C4—C5—H5B | 108.9 | H14A—C14—H14B | 109.5 |
C6—C5—H5B | 108.9 | C7—C14—H14C | 109.5 |
H5A—C5—H5B | 107.7 | H14A—C14—H14C | 109.5 |
C5—C6—C7 | 119.33 (13) | H14B—C14—H14C | 109.5 |
C5—C6—H6A | 107.5 | C7—C15—H15A | 109.5 |
C7—C6—H6A | 107.5 | C7—C15—H15B | 109.5 |
C5—C6—H6B | 107.5 | H15A—C15—H15B | 109.5 |
C7—C6—H6B | 107.5 | C7—C15—H15C | 109.5 |
H6A—C6—H6B | 107.0 | H15A—C15—H15C | 109.5 |
C14—C7—C15 | 108.17 (13) | H15B—C15—H15C | 109.5 |
C14—C7—C6 | 110.16 (12) | C10—C16—H16A | 109.5 |
C15—C7—C6 | 105.63 (12) | C10—C16—H16B | 109.5 |
C14—C7—C8 | 112.60 (11) | H16A—C16—H16B | 109.5 |
C15—C7—C8 | 109.25 (11) | C10—C16—H16C | 109.5 |
C6—C7—C8 | 110.74 (12) | H16A—C16—H16C | 109.5 |
C9—C8—C1 | 109.11 (10) | H16B—C16—H16C | 109.5 |
C9—C8—C7 | 112.79 (12) | ||
C12—C1—C2—C3 | 111.44 (11) | C3—C1—C8—C7 | 67.20 (16) |
C8—C1—C2—C3 | −110.21 (12) | C2—C1—C8—C7 | 136.14 (12) |
C1—C2—C3—C4 | 108.01 (14) | C12—C1—C8—C7 | −85.61 (13) |
C1—C2—C3—C13 | −109.34 (14) | C14—C7—C8—C9 | −80.64 (14) |
C12—C1—C3—C2 | −102.54 (14) | C15—C7—C8—C9 | 39.58 (15) |
C8—C1—C3—C2 | 106.03 (12) | C6—C7—C8—C9 | 155.52 (11) |
C2—C1—C3—C4 | −107.58 (13) | C14—C7—C8—C1 | 47.41 (16) |
C12—C1—C3—C4 | 149.87 (13) | C15—C7—C8—C1 | 167.63 (12) |
C8—C1—C3—C4 | −1.55 (17) | C6—C7—C8—C1 | −76.43 (14) |
C2—C1—C3—C13 | 108.24 (15) | C1—C8—C9—C10 | −17.09 (19) |
C12—C1—C3—C13 | 5.7 (2) | C7—C8—C9—C10 | 115.13 (15) |
C8—C1—C3—C13 | −145.73 (13) | C8—C9—C10—C11 | −4.7 (2) |
C2—C3—C4—C5 | −134.89 (13) | C8—C9—C10—C16 | 175.72 (16) |
C1—C3—C4—C5 | −65.84 (15) | C9—C10—C11—O1 | −179.74 (16) |
C13—C3—C4—C5 | 80.48 (16) | C16—C10—C11—O1 | −0.1 (2) |
C3—C4—C5—C6 | 84.92 (16) | C9—C10—C11—C12 | −0.8 (2) |
C4—C5—C6—C7 | −65.63 (18) | C16—C10—C11—C12 | 178.82 (15) |
C5—C6—C7—C14 | −66.50 (18) | O1—C11—C12—C1 | −153.30 (16) |
C5—C6—C7—C15 | 176.90 (14) | C10—C11—C12—C1 | 27.8 (2) |
C5—C6—C7—C8 | 58.73 (16) | C3—C1—C12—C11 | 156.43 (13) |
C3—C1—C8—C9 | −163.00 (11) | C2—C1—C12—C11 | 88.68 (15) |
C2—C1—C8—C9 | −94.06 (13) | C8—C1—C12—C11 | −50.76 (17) |
C12—C1—C8—C9 | 44.19 (14) |
D—H···A | D—H | H···A | D···A | D—H···A |
C2—H2B···O1i | 0.99 | 2.60 | 3.541 (2) | 160 |
Symmetry code: (i) −x+1, y+1/2, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
C2—H2B···O1i | 0.99 | 2.60 | 3.541 (2) | 159.8 |
Symmetry code: (i) −x+1, y+1/2, −z+1. |
References
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
α,β-unsaturated ketones are versatile intermediates in organic synthesis, since they are important precursors in the synthesis of enaminones (Auhmani et al., 2002), prodrugs (Danyang et al., 2007) and natural compounds (Tetsuhiro et al., 2003).
With the aim of preparing a new α,β-unsaturated ketone with sesquiterpenic skeleton, we report here the synthesis of (1R,3S,8R)-3,7,7,10-tetramethyltricyclo[6.4.0.01.3]dodec-9-en-11-one, 1. (1S,3S,8R)-3,7,7,10-tetramethyltricyclo[6.4.0.01,3]dodec-9-ene, 2, was treated with N-bromosuccinimide (NBS). The reaction was conducted at 0°C to provide the α,β-unsaturated ketone 1 as colorless crystals in 62% yield. Its structure was characterized by its mass and NMR spectroscopic data. Furthermore, an X-ray single-crystal structure analysis allowed its complete identification as (1R,3S,8R)-3,7,7,10-tetramethyltricyclo[6.4.0.01.3]dodec-9-en-11-one.
A view of the molecule is represented in Fig. 1. As observed in related compounds (Gassman & Gorman, 1990; Lassaba et al., 1997; Benharref et al., 2012), each molecule is built up from two fused six-and seven-membered rings. The six-membered ring has roughly half-chair conformation with the puckering parameters: Q = 0.4166 (11) Å, spherical polar angle θ = 124.02 (15)° and φ = 170.57 (19)° (Spek, 2009; Cremer & Pople, 1975), whereas the seven-membered ring displays a chair conformation with a total puckering amplitude of 0.7919 (11) Å (Evans & Boeyens, 1989).
There is a weak C—H···O hydrogen bond, which builds up a zigzag-like chain developing along the b axis (Table 1, Fig. 2)