(11SR,13RS)-12-Oxa-9-aza­tetra­cyclo[7.4.1.0^2,7.0^11,13]tetra­deca-2(7),3,5-trien-8-one

The title compound, C₁₃H₁₃NO₂, was prepared by the epoxidation of its racemic precursor. Its structure was determined in order to establish which of two diastereomers would be favored in that reaction and in other reactions of inter­est. The presence of inter­molecular C—H...O inter­actions was considered probable, although H-atom positions were not refined. These inter­actions link the mol­ecules into a two-dimensional network.

Key indicators

• Single-crystal X-ray study
• T = 150 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.038
• wR factor = 0.105
• Data-to-parameter ratio = 8.0

checkCIF/PLATON results

No syntax errors found



Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           27.47
           From the CIF: _reflns_number_total               1166
           Count of symmetry unique reflns         1167
           Completeness (_total/calc)             99.91%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured         0
           Fraction of Friedel pairs measured     0.000
           Are heavy atom types Z>Si present         no
PLAT792_ALERT_1_G Check the Absolute Configuration of C1     = ...          S
PLAT792_ALERT_1_G Check the Absolute Configuration of C11    = ...          S
PLAT792_ALERT_1_G Check the Absolute Configuration of C13    = ...          R
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          2

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   0 ALERT level C = Check and explain
   5 ALERT level G = General alerts; check

   3 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Chemical schemes of compounds (I), (II), (III) and (IV) are drawn in Fig. 2. The constrained placement of a lactam nitrogen at a bridgehead position in a relatively small bi- or tri-cyclic framework is known to give rise to an appreciable increase in solvolytic reactivity (Greenberg, 1988) (Greenberg et al., 2000). This behavior has been properly attributed to the geometrically enforced loss of amide resonance (Tani & Stoltz, 2006), the cost of which can rise as high as 16–22 kcal/mol (Winkler & Dunitz, 1971). As a result, the carbonyl group in the most extreme cases (Kirby et al., 1998) is decidedly ketone-like in its spectroscopic and chemical properties. The search for other unconventional behavior by compounds of this general class has more recently been directed to the consequences of photoactivation (Paquette et al., 2006). The presence of a diene chromophore as in (I) was designed to enhance the absorption of light energy. When irradiated at 300 nm in hexane, (I) experiences stereoselective disrotatory cyclization to give initially (II), this pathway representing a significant departure from the response of the corresponding sultam, which undergoes SO₂–N bond homolysis and subsequent structural reorganization principally (Paquette et al., 2006).

The synthetic protocol that gives rise to (I) proceeds via racemic 9-azatricyclo[7.4.1.0^2,7] tetradeca-2,4,6,11-tetraen-8-one, (III). This intermediate is characterized by the presence of an isolated double bond that is amenable in principle to electrophilic attack from the top and/or bottom surface. Since the conversion of (III) to (I) has to be accomplished by chemical modification of this sector of the lactam, it was considered advisable to clarify which approach to (I) is kinetically preferred. Epoxidation with m-chloroperbenzoic acid proved to be a suitable probe experiment, affording (IV) almost exclusively in an efficient manner. The stereochemistry of (IV) was established by X-ray crystallographic analysis as detailed herein.

The bond distances are in agreement with those selected in the critical evaluation of structures of organic molecules in the Cambridge data base (Allen et al.,1987). The phenyl ring is fused through C(2) and C(7) to the aliphatic remainder of the molecule. The geometry of epoxide molecules has been extensively discussed (Allen, 1982). The possible presence of C–H···O hydrogen bonds was considered although H-atom positions were not refined. The hydrogen positions were calculated using values provided by SHELXL97 (Sheldrick, 1997). The shortest intermolecular value found was 2.45 Å with C–H···O 156° calculated using PARST (Nardelli, 1995) as given in WinGX2005 (Farrugia, 1999). The value was normalized in PARST (Taylor & Kennard, 1983) to yield estimates of 2.37 Å and 155°, appropriate for comparison to neutron diffraction results. These values fall within the range of such numbers as discussed earlier (Steiner & Saenger, 1992). Table 2 contains these possible C–H···O hydrogen bonds and Fig.3 shows a portion of the H-bond two dimensional network.

Related literature

For related chemistry, see: Greenberg (1988); Greenberg et al. (2000); Kirby et al. (1998); Paquette et al. (2006); Tani & Stoltz (2006); Winkler & Dunitz (1971). For related literature on geometry, see: Allen (1982); Allen et al. (1987); Nardelli (1995); Sheldrick (1997); Steiner & Saenger (1992); Taylor & Kennard (1983)

S2. Experimental

To a solution of (III) (0.19 g) in dichloromethane (20 ml) was added m-chloroperbenzoic acid (0.26 g) and NaHCO₃ (0.16 g). After being stirred overnight, the reaction mixture was poured into a saturated solution of Na₂SO₃ (10 ml) and dichloromethane (100 ml). The resulting organic phase was dried, freed of solvent under reduced pressure, and purified by column chromatography on silica gel (ether elution). Epoxide (IV) was isolated as a white solid (0.17 g, 83%) having a melting point of 129–131 C.

S3. Refinement

The hydrogen atoms were included in the model at calculated positions using a riding model with U(H) = 1.2 * U_eq(attached atom).

Computing details

Data collection: COLLECT (Nonius, 1999); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: SCALEPACK and DENZO (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1999); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

	Fig. 1. The molecular structure of (IV), with atom labels and 50% probability displacement ellipsoids for non-H atoms.
	Fig. 2. Chemical schemes for (I), (II), (III) and (IV). Hydrogen atoms are not shown.
	Fig. 3. A portion of the intermolecular hydrogen bond network.

(11SR,13RS)-12-Oxa-9- azatetracyclo[7.4.1.0^2,7.0^11,13]tetradeca-2(7),3,5-trien-8-one

Crystal data

C13H13NO2	F(000) = 456
Mr = 215.24	Dx = 1.412 Mg m^−3
Monoclinic, Cc	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: C -2yc	Cell parameters from 1207 reflections
a = 7.1597 (10) Å	θ = 2.0–27.5°
b = 16.533 (3) Å	µ = 0.10 mm^−1
c = 8.7277 (10) Å	T = 150 K
β = 101.364 (11)°	Arrowhead-shaped chunk, colourless
V = 1012.8 (3) Å^3	0.35 × 0.23 × 0.12 mm
Z = 4

Data collection

Nonius KappaCCD area-detector diffractometer	1166 independent reflections
Radiation source: Enraf–Nonius FR590	1069 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.032
Detector resolution: 9 pixels mm^-1	θmax = 27.5°, θmin = 2.5°
φ and ω scans	h = −9→9
Absorption correction: multi-scan (SCALEPACK; Otwinowski & Minor, 1997)	k = −21→21
Tmin = 0.933, Tmax = 0.989	l = −11→11
10172 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.038	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.105	H-atom parameters constrained
S = 1.02	w = 1/[σ^2(Fo^2) + (0.0754P)^2 + 0.2542P] where P = (Fo^2 + 2Fc^2)/3
1166 reflections	(Δ/σ)max = 0.002
145 parameters	Δρmax = 0.19 e Å^−3
2 restraints	Δρmin = −0.18 e Å^−3

Special details

Experimental. The data collection crystal was a clear, colorless arrowhead-shaped chunk. Examination of the diffraction pattern on a Nonius Kappa CCD diffractometer indicated a monoclinic crystal system. All work was done at 150 K using an Oxford Cryosystems Cryostream Cooler. The data collection strategy was set up to measure a quadrant of reciprocal space with a redundancy factor of 4.8, which means that 90% of the reflections were measured at least 4.8 times. A combination of phi and omega scans with a frame width of 1.0 degree was used. Data integration was done with DENZO (Otwinowski & Minor, 1997) and scaling and merging of the data was done with SCALEPACK (Otwinowski & Minor, 1997).

The structure was solved by the direct methods procedure in SHELXS97 (Sheldrick, 1997) in space group Cc. Full-matrix least-squares refinements based on F² were performed in SHELXL97 (Sheldrick, 1997), as incorporated in the WinGX package(Farrugia, 1999).

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.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
C8	0.2248 (4)	0.14357 (15)	0.0988 (3)	0.0241 (5)
C7	0.0275 (4)	0.12148 (14)	0.0165 (3)	0.0226 (5)
C6	−0.0335 (4)	0.13839 (14)	−0.1410 (3)	0.0277 (6)
H6	0.0542	0.1584	−0.2006	0.033*
C5	−0.2230 (4)	0.12614 (17)	−0.2118 (3)	0.0327 (6)
H5	−0.2647	0.1375	−0.3199	0.039*
C4	−0.3513 (4)	0.09735 (17)	−0.1245 (3)	0.0326 (6)
H4	−0.4808	0.089	−0.173	0.039*
C3	−0.2908 (4)	0.08056 (16)	0.0343 (3)	0.0281 (5)
H3	−0.3796	0.0611	0.0934	0.034*
C2	−0.1011 (3)	0.09220 (14)	0.1068 (3)	0.0221 (5)
C1	−0.0226 (3)	0.07768 (14)	0.2782 (3)	0.0222 (5)
H1	−0.1065	0.0387	0.3206	0.027*
C14	−0.0146 (3)	0.15923 (16)	0.3686 (3)	0.0268 (5)
H14A	−0.0397	0.2027	0.2891	0.032*
H14B	−0.1233	0.1592	0.4233	0.032*
C13	0.1604 (4)	0.18480 (16)	0.4879 (3)	0.0258 (5)
H13	0.1364	0.2332	0.5499	0.031*
C11	0.3621 (4)	0.17497 (15)	0.4812 (3)	0.0264 (5)
H11	0.4462	0.2181	0.5382	0.032*
C10	0.4408 (4)	0.13582 (16)	0.3511 (3)	0.0264 (5)
H10A	0.5112	0.177	0.3026	0.032*
H10B	0.5325	0.0932	0.396	0.032*
C15	0.1720 (3)	0.03971 (14)	0.2840 (3)	0.0231 (5)
H15A	0.2277	0.0228	0.3921	0.028*
H15B	0.16	−0.0086	0.2157	0.028*
N9	0.2944 (3)	0.10007 (12)	0.2303 (2)	0.0228 (5)
O16	0.3117 (3)	0.19990 (12)	0.0526 (2)	0.0329 (4)
O12	0.2746 (3)	0.12359 (12)	0.5828 (2)	0.0286 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C8	0.0247 (12)	0.0231 (12)	0.0263 (11)	0.0001 (9)	0.0092 (9)	−0.0015 (10)
C7	0.0261 (12)	0.0198 (11)	0.0230 (11)	0.0018 (9)	0.0076 (9)	−0.0024 (9)
C6	0.0373 (14)	0.0226 (12)	0.0245 (13)	0.0032 (10)	0.0094 (11)	0.0011 (10)
C5	0.0409 (16)	0.0318 (14)	0.0232 (12)	0.0083 (11)	0.0009 (11)	−0.0039 (10)
C4	0.0287 (14)	0.0347 (15)	0.0313 (14)	0.0049 (11)	−0.0014 (11)	−0.0058 (11)
C3	0.0261 (13)	0.0291 (13)	0.0295 (12)	0.0005 (10)	0.0064 (10)	−0.0061 (11)
C2	0.0262 (12)	0.0184 (11)	0.0225 (11)	0.0017 (9)	0.0069 (9)	−0.0011 (9)
C1	0.0226 (11)	0.0220 (12)	0.0231 (11)	−0.0013 (9)	0.0070 (9)	0.0008 (9)
C14	0.0260 (12)	0.0317 (13)	0.0236 (12)	0.0031 (10)	0.0072 (9)	−0.0047 (11)
C13	0.0303 (13)	0.0251 (12)	0.0228 (12)	0.0024 (10)	0.0070 (10)	0.0017 (9)
C11	0.0269 (12)	0.0229 (12)	0.0286 (12)	−0.0035 (10)	0.0033 (9)	0.0031 (10)
C10	0.0208 (12)	0.0280 (13)	0.0299 (13)	−0.0014 (9)	0.0039 (9)	0.0013 (10)
C15	0.0235 (12)	0.0177 (10)	0.0288 (12)	0.0001 (9)	0.0071 (9)	0.0026 (9)
N9	0.0214 (11)	0.0218 (10)	0.0259 (10)	−0.0003 (8)	0.0068 (8)	0.0022 (8)
O16	0.0335 (10)	0.0309 (10)	0.0369 (10)	−0.0076 (8)	0.0134 (8)	0.0052 (8)
O12	0.0306 (10)	0.0303 (10)	0.0243 (9)	−0.0009 (7)	0.0042 (7)	0.0059 (7)

Geometric parameters (Å, º)

C8—O16	1.231 (3)	C1—H1	1
C8—N9	1.363 (3)	C14—C13	1.523 (4)
C8—C7	1.498 (3)	C14—H14A	0.99
C7—C6	1.387 (4)	C14—H14B	0.99
C7—C2	1.411 (3)	C13—O12	1.453 (3)
C6—C5	1.391 (4)	C13—C11	1.465 (4)
C6—H6	0.95	C13—H13	1
C5—C4	1.389 (4)	C11—O12	1.456 (3)
C5—H5	0.95	C11—C10	1.510 (4)
C4—C3	1.396 (4)	C11—H11	1
C4—H4	0.95	C10—N9	1.457 (3)
C3—C2	1.394 (3)	C10—H10A	0.99
C3—H3	0.95	C10—H10B	0.99
C2—C1	1.510 (3)	C15—N9	1.465 (3)
C1—C15	1.520 (3)	C15—H15A	0.99
C1—C14	1.557 (3)	C15—H15B	0.99
O16—C8—N9	123.4 (2)	C1—C14—H14B	106.8
O16—C8—C7	121.1 (2)	H14A—C14—H14B	106.7
N9—C8—C7	115.4 (2)	O12—C13—C11	59.83 (16)
C6—C7—C2	120.7 (2)	O12—C13—C14	119.4 (2)
C6—C7—C8	120.6 (2)	C11—C13—C14	128.8 (2)
C2—C7—C8	118.3 (2)	O12—C13—H13	112.7
C7—C6—C5	120.0 (2)	C11—C13—H13	112.7
C7—C6—H6	120	C14—C13—H13	112.7
C5—C6—H6	120	O12—C11—C13	59.67 (16)
C4—C5—C6	119.9 (2)	O12—C11—C10	118.5 (2)
C4—C5—H5	120	C13—C11—C10	126.4 (2)
C6—C5—H5	120	O12—C11—H11	113.7
C5—C4—C3	120.3 (2)	C13—C11—H11	113.7
C5—C4—H4	119.9	C10—C11—H11	113.7
C3—C4—H4	119.9	N9—C10—C11	113.4 (2)
C2—C3—C4	120.5 (2)	N9—C10—H10A	108.9
C2—C3—H3	119.8	C11—C10—H10A	108.9
C4—C3—H3	119.8	N9—C10—H10B	108.9
C3—C2—C7	118.6 (2)	C11—C10—H10B	108.9
C3—C2—C1	124.5 (2)	H10A—C10—H10B	107.7
C7—C2—C1	116.8 (2)	N9—C15—C1	108.09 (19)
C2—C1—C15	104.98 (19)	N9—C15—H15A	110.1
C2—C1—C14	109.5 (2)	C1—C15—H15A	110.1
C15—C1—C14	113.5 (2)	N9—C15—H15B	110.1
C2—C1—H1	109.6	C1—C15—H15B	110.1
C15—C1—H1	109.6	H15A—C15—H15B	108.4
C14—C1—H1	109.6	C8—N9—C10	119.1 (2)
C13—C14—C1	122.0 (2)	C8—N9—C15	119.1 (2)
C13—C14—H14A	106.8	C10—N9—C15	115.81 (19)
C1—C14—H14A	106.8	C13—O12—C11	60.50 (16)
C13—C14—H14B	106.8
O16—C8—C7—C6	26.4 (4)	C15—C1—C14—C13	−16.8 (3)
N9—C8—C7—C6	−156.8 (2)	C1—C14—C13—O12	−33.8 (3)
O16—C8—C7—C2	−146.0 (2)	C1—C14—C13—C11	39.6 (4)
N9—C8—C7—C2	30.7 (3)	C14—C13—C11—O12	−105.2 (3)
C2—C7—C6—C5	−0.3 (4)	O12—C13—C11—C10	104.8 (3)
C8—C7—C6—C5	−172.6 (2)	C14—C13—C11—C10	−0.4 (4)
C7—C6—C5—C4	0.3 (4)	O12—C11—C10—N9	66.7 (3)
C6—C5—C4—C3	0.0 (4)	C13—C11—C10—N9	−5.1 (4)
C5—C4—C3—C2	−0.2 (4)	C2—C1—C15—N9	65.8 (2)
C4—C3—C2—C7	0.2 (4)	C14—C1—C15—N9	−53.7 (3)
C4—C3—C2—C1	178.5 (2)	O16—C8—N9—C10	22.1 (4)
C6—C7—C2—C3	0.1 (3)	C7—C8—N9—C10	−154.6 (2)
C8—C7—C2—C3	172.5 (2)	O16—C8—N9—C15	173.8 (2)
C6—C7—C2—C1	−178.4 (2)	C7—C8—N9—C15	−2.9 (3)
C8—C7—C2—C1	−5.9 (3)	C11—C10—N9—C8	96.1 (3)
C3—C2—C1—C15	140.8 (2)	C11—C10—N9—C15	−56.4 (3)
C7—C2—C1—C15	−40.9 (3)	C1—C15—N9—C8	−45.9 (3)
C3—C2—C1—C14	−97.1 (3)	C1—C15—N9—C10	106.6 (2)
C7—C2—C1—C14	81.3 (3)	C14—C13—O12—C11	120.3 (2)
C2—C1—C14—C13	−133.7 (2)	C10—C11—O12—C13	−117.7 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C15—H15B···O12^i	0.99	2.45	3.379 (3)	156
C4—H4···O12^ii	0.95	2.54	3.345 (3)	142
C13—H13···O16^iii	1.00	2.58	3.278 (3)	127

Symmetry codes: (i) x, −y, z−1/2; (ii) x−1, y, z−1; (iii) x−1/2, −y+1/2, z+1/2.