2-(2-Naphth­yl)-1,3-dioxane

The title compound, C₁₄H₁₄O₂, crystallizes in the chiral monoclinic space group P2₁. This acetal is composed of a planar naphthalene ring with a 1,3-dioxane ring substituent, which has a chair conformation. In the crystal structure, symmetry-related mol­ecules are connected via a weak C-H...O inter­action to form a helical chain propagating in [010]. While there are no [pi]-[pi] stacking inter­actions present, there are weak C-H...[pi] inter­actions involving the naphthalene aromatic rings, which link the helical chains to form a two-dimensional network in the (011) plane.

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.024
• wR factor = 0.061
• Data-to-parameter ratio = 7.6

checkCIF/PLATON results

No syntax errors found



Alert level A
PLAT029_ALERT_3_A _diffrn_measured_fraction_theta_full Low .......       0.94

Author Response: ...Using the one-circle Stoe Image Plate Diffraction System it is not always possible to measure 100% of the Ewald sphere, and here only 93.7% of the data were accessible out to 50\% in 2\q. This has little effect on the bond distances and angles when comparing their values with those of the related structure mentioned in the Comment section (Borbas et al., 2002)

Alert level B
PLAT911_ALERT_3_B Missing # FCF Refl Between THmin & STh/L=  0.600         68

Alert level C
PLAT022_ALERT_3_C Ratio Unique / Expected Reflections too Low ....       0.93
PLAT089_ALERT_3_C Poor Data / Parameter Ratio (Zmax .LT. 18) .....       7.57
PLAT913_ALERT_3_C Missing # of Very Strong Reflections in FCF ....          4
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600          4

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           25.98
           From the CIF: _reflns_number_total               1098
           Count of symmetry unique reflns         1186
           Completeness (_total/calc)             92.58%
           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

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

   0 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
   5 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Acetals are the most commonly used protecting groups for carbonyl compounds in organic synthesis (Kocienski, 1994; Showler & Darley, 1967), and many methods have been developed for their deprotection (Cordes & Bull, 1974; Fujioka et al., 2004; Ates et al., 2003). The title 2-naphthaldehyde acetal (Newman & Dickson, 1970; Carmichael & Hug, 1986) was synthesized to investigate the scope of a new photochemical reaction capable of hydrolysing the acetal into an aldehyde (Thevenet & Neier, 2010). The NMR spectra of the unsubstituted 1,3-dioxane ring displays a complicated AA'BB'MN system (Buys & Eliel, 1970), and the X-ray crystal structure was helpful for the interpretation of the NMR spectra (Thevenet & Neier, 2010).

The structure of the title compound is illustrated in Fig. 1, and the geometrical parameters are given in the Supplementary information and the archived CIF. The bond lengths and angles are close to those in three similar compounds located in the Cambridge Crystal Structure Database (CSD, V 5.30, last update Sept. 2009; Allen, 2002). For example, methyl 2,3-di-O-acteyl-4,6-O-(2-naphthyl)methylene-α-D-galactopyranoside (Borbas et al., 2002), which also crystallized in the monoclinic space group P2₁, and where the naphthalene ring is planar and the two six-membered rings in the galactopyranoside unit have chair conformations.

In the crystal of the title compound symmetry related molecules are connected via a C—H···O interaction (Table 1) giving rise to the formation of helical chains propagating in [010]. These chains are further linked via weak C—H···π interactions to form a two-dimensional network in (011) - see Fig. 2 and Table 1 for details.

Related literature

For information on commonly used protecting groups for carbonyl compounds, see: Kocienski (1994); Showler & Darley (1967). For methods for their deprotection, see: Cordes & Bull (1974); Fujioka et al. (2004); Ates et al. (2003). For kinetic and thermodynamic studies of acetals and ketals in the naphthalene series and other physical data, see: Newman & Dickson (1970); Carmichael & Hug (1986). For the synthesis of 2-naphthaldehyde acetal, see Gopinath et al. (2002). For details of the new photochemical reaction to hydrolyse the acetal into an aldehyde, see Thevenet & Neier (2010). For information on 1,3-dioxane ring related compounds, see: Buys & Eliel (1970). For the synthesis and crystal structure of a related compound, see: Borbas et al. (2002). For normal geometric parameters for molecular compounds, see: Allen (2002).

S2. Experimental

The title compound was synthesized using a modified strategy described by (Gopinath et al., 2002). To a solution of 2-naphthaldehyde (0.64 mmol), trimethylorthoformate (1.41 mmol) and 1,3-propanediol (5.12 mmol) in dry nitromethane (2 ml) was added tetrabutylammonium tribromide (0.025 mmol). The homogeneous reaction mixture was stirred at r.t. and the progress of the reaction monitored by TLC and GC. After completion of the reaction the mixture was poured into a solution of NaHCO₃ (10 ml) and the products were extracted with diethyl ether (3 × 10 ml). The organic layer was separated, dried over anhydrous Na₂SO₄ and concentrated. The white solid obtained was purified by recrystallization in MeOH, giving colourless thin plate-like crystals of the title compound.

¹H NMR 400 MHz (CDCl₃) δ 7.97 (br s, 1H, H_1'), 7.85 (m, 3H, H_4',5',8'), 7.60 (dd, 1H, ³J_3'-4' = 8.5 Hz, ³J_3'-1' = 1.7 Hz, H_3'), 7.48 (m, 2H, H_6',7'), 5.68 (s, 1H, H₁), 4.33 (dddd, 2H, ²J_3e-3a;5e-5a = -11.7 Hz, ³J_3e-4a;5e-4a = 5.0 Hz, ³J_3e-4e;5e-4e = 1.5 Hz, ⁴J_3e-5e = 3.0 Hz, H_3e,5e), 4.06 (ddd, 2H, ²J_3a-3e;5a-5e = -11.7 Hz, ³J_3a-4a;5a-4a = 12.4 Hz, ³J_3a-4e;5a-4e = 2.7 Hz, H_3a,5a), 2.29( dtt, 1H, ²J_4a-4e = -13.5 Hz, ³J_4a-3a;4a-5a = 12.4 Hz, ³J_4a-3e;4a-5e = 5.0 Hz, H_4a), 1.50 (dtt, 1H, ²J_4e-4a = -13.5 Hz, ³J_4e-3a;4e-5a = 2.7 Hz, ³J_4e-3e;4e-5e = 1.5 Hz, H_{4 e}); ¹³C NMR 100 MHz (CDCl₃) δ 136.1 (C_2'), (133.6, 133.1) (C_9',10'), (128.4, 128.1, 127.7) (C_4',5',8'), (126.2, 126.0) (C_6',7'), 125.3 (C_1'), 123.8 (C_3'), 101.8 (C₁), 67.5 (C_3,5), 25.9 (C₄); HRMS (ESI, +): [M + Na]⁺ = 237.09. Note: The same numbering scheme has been used for the crystal structure (Fig. 1). The torsional angles of the 1,3-dioxane ring were measured to estimate the coupling constants according to the Karplus equation.

S3. Refinement

In the final cycles of refinement, in the absence of significant anomalous scattering effects, 944 (93%) Friedel pairs were merged and Δf" set to zero. The H-atoms could all be located in difference electron-density maps. In the final cycles of refinement they were included in calculated positions and treated as riding atoms: C—H = 0.95–1.0 Å, with U_iso(H) = 1.2U_eq(parent C-atom). Using the one-circle Stoe Image Plate Diffraction System it is not always possible to measure 100% of the Ewald sphere, and here only 93.7% of the data were accessible out to 50° in 2θ. This has little effect on the bond distances and angles when comparing their values with those of the related structure mentioned above (Borbas et al., 2002).

Computing details

Data collection: EXPOSE in IPDS-I (Stoe & Cie, 2000); cell refinement: CELL in IPDS-I (Stoe & Cie, 2000); data reduction: INTEGRATE in IPDS-I (Stoe & Cie, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009) and Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures

Fig. 1. A view of the molecular structure of the title compound, with displacement ellipoids drawn at the 50% probabilty level.

Fig. 2. A view along the a axis of the crystal packing of the title compound. The C—H···O and C—H···π interactions are shown as dotted cyan and black lines, respectively. [The blue balls represent the centroids of the two aromatic rings; H-atoms not involved in the C—H···O and C—H···π interactions have been omitted for clarity; the C—H···π interactions are shown for one molecule only; see Table 1 for details].

2-(2-Naphthyl)-1,3-dioxane

Crystal data

C14H14O2	F(000) = 228
Mr = 214.25	Dx = 1.279 Mg m^−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 4553 reflections
a = 7.5351 (6) Å	θ = 2.1–26.0°
b = 7.8575 (8) Å	µ = 0.08 mm^−1
c = 9.4057 (9) Å	T = 173 K
β = 92.839 (11)°	Plate, colourless
V = 556.20 (9) Å^3	0.38 × 0.30 × 0.08 mm
Z = 2

Data collection

Stoe IPDS diffractometer	951 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.024
Graphite monochromator	θmax = 26.0°, θmin = 2.2°
φ rotation scans	h = −8→8
4461 measured reflections	k = −9→9
1098 independent reflections	l = −11→11

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)] = 0.024	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.061	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0412P)^2] where P = (Fo^2 + 2Fc^2)/3
1098 reflections	(Δ/σ)max < 0.001
145 parameters	Δρmax = 0.13 e Å^−3
1 restraint	Δρmin = −0.11 e Å^−3

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

Refinement. In the final cycles of refinement, in the absence of significant anomalous scattering effects, 944 (93%) Friedel pairs were merged and Δf " set to zero. The H-atoms could all be located in difference electron-density maps. In the final cycles of refinement they were included in calculated positions and treated as riding atoms: C—H = 0.95 - 1.0 Å, with U_iso(H) = 1.2U_eq(parent C-atoms). Using the one-circle Stoe Image Plate Diffraction System it is not always possible to measure 100% of the Ewald sphere, and here only 93.7% of the data were accessible out to 50° in 2θ.

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

	x	y	z	Uiso*/Ueq
O2	1.16506 (19)	0.57058 (16)	0.43163 (12)	0.0337 (4)
O6	1.33418 (18)	0.38156 (15)	0.57014 (12)	0.0295 (4)
C1	1.1616 (2)	0.4392 (2)	0.53276 (17)	0.0251 (5)
C1'	0.9100 (2)	0.46504 (19)	0.69218 (16)	0.0239 (5)
C2'	1.0796 (2)	0.5075 (2)	0.66364 (16)	0.0240 (5)
C3	1.2305 (3)	0.5057 (3)	0.30168 (18)	0.0417 (7)
C3'	1.1796 (3)	0.6163 (2)	0.75664 (17)	0.0277 (6)
C4	1.4131 (3)	0.4321 (3)	0.32815 (19)	0.0400 (7)
C4'	1.1073 (3)	0.6764 (2)	0.87667 (18)	0.0297 (6)
C5	1.4128 (3)	0.3067 (3)	0.44944 (18)	0.0348 (6)
C5'	0.8555 (3)	0.6908 (2)	1.03543 (18)	0.0309 (6)
C6'	0.6865 (3)	0.6467 (2)	1.06380 (18)	0.0316 (6)
C7'	0.5852 (3)	0.5438 (2)	0.96939 (18)	0.0328 (6)
C8'	0.6551 (2)	0.4853 (2)	0.84779 (18)	0.0284 (5)
C9'	0.8310 (2)	0.52609 (19)	0.81562 (16)	0.0236 (5)
C10'	0.9334 (2)	0.63231 (19)	0.91039 (17)	0.0239 (5)
H1	1.08840	0.34250	0.49320	0.0300*
H1'	0.84350	0.39320	0.62810	0.0290*
H3'	1.29720	0.64750	0.73540	0.0330*
H3A	1.14900	0.41670	0.26250	0.0500*
H3E	1.23480	0.59870	0.23090	0.0500*
H4'	1.17550	0.74940	0.93860	0.0360*
H4A	1.45060	0.37410	0.24110	0.0480*
H4E	1.49890	0.52450	0.35160	0.0480*
H5'	0.92210	0.76160	1.10020	0.0370*
H5A	1.53630	0.27170	0.47590	0.0420*
H5E	1.34500	0.20400	0.41910	0.0420*
H6'	0.63660	0.68620	1.14860	0.0380*
H7'	0.46700	0.51460	0.99020	0.0390*
H8'	0.58470	0.41640	0.78400	0.0340*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O2	0.0500 (9)	0.0289 (6)	0.0225 (6)	0.0088 (6)	0.0049 (5)	0.0012 (5)
O6	0.0283 (8)	0.0376 (7)	0.0228 (5)	0.0058 (6)	0.0027 (5)	−0.0007 (5)
C1	0.0269 (11)	0.0239 (8)	0.0244 (8)	−0.0013 (6)	0.0008 (7)	0.0000 (6)
C1'	0.0245 (11)	0.0228 (8)	0.0240 (8)	−0.0016 (6)	−0.0023 (7)	0.0007 (6)
C2'	0.0265 (11)	0.0229 (8)	0.0225 (8)	−0.0003 (7)	0.0012 (7)	0.0021 (7)
C3	0.0679 (17)	0.0358 (9)	0.0220 (8)	0.0095 (10)	0.0084 (9)	0.0013 (8)
C3'	0.0224 (11)	0.0303 (9)	0.0307 (9)	−0.0050 (7)	0.0031 (7)	−0.0032 (7)
C4	0.0533 (16)	0.0374 (10)	0.0306 (9)	−0.0015 (9)	0.0158 (9)	−0.0061 (8)
C4'	0.0273 (12)	0.0299 (9)	0.0317 (9)	−0.0050 (7)	−0.0007 (7)	−0.0058 (7)
C5	0.0371 (13)	0.0395 (10)	0.0283 (9)	0.0069 (8)	0.0077 (8)	−0.0053 (8)
C5'	0.0345 (14)	0.0286 (9)	0.0298 (9)	0.0016 (7)	0.0026 (8)	−0.0023 (7)
C6'	0.0322 (12)	0.0327 (9)	0.0309 (8)	0.0066 (8)	0.0105 (7)	0.0024 (7)
C7'	0.0230 (12)	0.0382 (11)	0.0377 (9)	0.0031 (7)	0.0063 (8)	0.0075 (8)
C8'	0.0222 (11)	0.0316 (9)	0.0313 (8)	−0.0035 (8)	0.0004 (7)	0.0029 (7)
C9'	0.0222 (11)	0.0226 (8)	0.0257 (8)	0.0007 (6)	−0.0005 (7)	0.0051 (6)
C10'	0.0242 (11)	0.0211 (7)	0.0264 (8)	0.0010 (7)	0.0013 (7)	0.0007 (6)

Geometric parameters (Å, º)

O2—C1	1.405 (2)	C8'—C9'	1.411 (2)
O2—C3	1.434 (2)	C9'—C10'	1.421 (2)
O6—C1	1.405 (2)	C1—H1	1.0000
O6—C5	1.433 (2)	C1'—H1'	0.9500
C1—C2'	1.504 (2)	C3—H3A	0.9900
C1'—C2'	1.360 (2)	C3—H3E	0.9900
C1'—C9'	1.415 (2)	C3'—H3'	0.9500
C2'—C3'	1.414 (2)	C4—H4A	0.9900
C3—C4	1.502 (3)	C4—H4E	0.9900
C3'—C4'	1.362 (3)	C4'—H4'	0.9500
C4—C5	1.508 (3)	C5—H5A	0.9900
C4'—C10'	1.407 (3)	C5—H5E	0.9900
C5'—C6'	1.359 (3)	C5'—H5'	0.9500
C5'—C10'	1.417 (2)	C6'—H6'	0.9500
C6'—C7'	1.399 (3)	C7'—H7'	0.9500
C7'—C8'	1.363 (2)	C8'—H8'	0.9500
C1—O2—C3	109.55 (14)	C9'—C1'—H1'	119.00
C1—O6—C5	110.36 (13)	O2—C3—H3A	110.00
O2—C1—O6	110.99 (13)	O2—C3—H3E	110.00
O2—C1—C2'	108.32 (13)	C4—C3—H3A	110.00
O6—C1—C2'	108.84 (13)	C4—C3—H3E	110.00
C2'—C1'—C9'	121.09 (14)	H3A—C3—H3E	108.00
C1—C2'—C1'	120.15 (14)	C2'—C3'—H3'	120.00
C1—C2'—C3'	119.63 (14)	C4'—C3'—H3'	120.00
C1'—C2'—C3'	120.22 (15)	C3—C4—H4A	110.00
O2—C3—C4	110.27 (15)	C3—C4—H4E	110.00
C2'—C3'—C4'	119.98 (19)	C5—C4—H4A	110.00
C3—C4—C5	109.96 (18)	C5—C4—H4E	110.00
C3'—C4'—C10'	121.12 (17)	H4A—C4—H4E	108.00
O6—C5—C4	110.33 (18)	C3'—C4'—H4'	119.00
C6'—C5'—C10'	120.74 (16)	C10'—C4'—H4'	119.00
C5'—C6'—C7'	120.65 (17)	O6—C5—H5A	110.00
C6'—C7'—C8'	120.42 (19)	O6—C5—H5E	110.00
C7'—C8'—C9'	120.64 (16)	C4—C5—H5A	110.00
C1'—C9'—C8'	122.48 (14)	C4—C5—H5E	110.00
C1'—C9'—C10'	118.47 (14)	H5A—C5—H5E	108.00
C8'—C9'—C10'	119.06 (14)	C6'—C5'—H5'	120.00
C4'—C10'—C5'	122.42 (15)	C10'—C5'—H5'	120.00
C4'—C10'—C9'	119.09 (14)	C5'—C6'—H6'	120.00
C5'—C10'—C9'	118.49 (15)	C7'—C6'—H6'	120.00
O2—C1—H1	110.00	C6'—C7'—H7'	120.00
O6—C1—H1	110.00	C8'—C7'—H7'	120.00
C2'—C1—H1	110.00	C7'—C8'—H8'	120.00
C2'—C1'—H1'	119.00	C9'—C8'—H8'	120.00
C3—O2—C1—O6	64.83 (17)	O2—C3—C4—C5	51.9 (2)
C3—O2—C1—C2'	−175.74 (14)	C2'—C3'—C4'—C10'	−0.1 (3)
C1—O2—C3—C4	−58.4 (2)	C3—C4—C5—O6	−50.8 (2)
C5—O6—C1—O2	−64.14 (17)	C3'—C4'—C10'—C5'	179.07 (16)
C5—O6—C1—C2'	176.74 (14)	C3'—C4'—C10'—C9'	−1.3 (2)
C1—O6—C5—C4	56.5 (2)	C10'—C5'—C6'—C7'	−0.6 (3)
O2—C1—C2'—C1'	104.47 (17)	C6'—C5'—C10'—C4'	179.42 (16)
O2—C1—C2'—C3'	−75.40 (18)	C6'—C5'—C10'—C9'	−0.2 (2)
O6—C1—C2'—C1'	−134.75 (15)	C5'—C6'—C7'—C8'	0.4 (3)
O6—C1—C2'—C3'	45.38 (19)	C6'—C7'—C8'—C9'	0.6 (2)
C9'—C1'—C2'—C1	179.19 (14)	C7'—C8'—C9'—C1'	178.60 (15)
C9'—C1'—C2'—C3'	−0.9 (2)	C7'—C8'—C9'—C10'	−1.4 (2)
C2'—C1'—C9'—C8'	179.59 (15)	C1'—C9'—C10'—C4'	1.6 (2)
C2'—C1'—C9'—C10'	−0.5 (2)	C1'—C9'—C10'—C5'	−178.80 (14)
C1—C2'—C3'—C4'	−178.90 (15)	C8'—C9'—C10'—C4'	−178.48 (15)
C1'—C2'—C3'—C4'	1.2 (2)	C8'—C9'—C10'—C5'	1.2 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C1′—H1′···O2^i	0.95	2.60	3.349 (2)	136
C5′—H5′···Cg1^ii	0.95	2.70	3.555 (2)	151
C4′—H4′···Cg2^ii	0.95	2.92	3.776 (2)	150
C3—H3A···Cg1^i	0.99	2.99	3.927 (2)	159

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