(2S,4S)-3-Benzoyl-4-benzyl-2-tert-but­yl-1,3-oxazolidin-5-one

Dungan, V.J.; Mueller-Bunz, H.; Rutledge, P.J.

doi:10.1107/S1600536812035556

organic compounds

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ISSN: 2056-9890

Volume 68| Part 9| September 2012| Page o2747

doi:10.1107/S1600536812035556

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(2S,4S)-3-Benzoyl-4-benzyl-2-tert-butyl-1,3-oxazolidin-5-one

Victoria J. Dungan,^a Helge Mueller-Bunz ^b and Peter J. Rutledge ^a ^*

^aSchool of Chemistry, The University of Sydney, NSW 2006, Australia, and ^bSchool of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland
^*Correspondence e-mail: peter.rutledge@sydney.edu.au

(Received 30 May 2012; accepted 13 August 2012; online 23 August 2012)

In the title compound, C₂₁H₂₃NO₃, the central oxazolidinone ring is approximately planar, the maximum deviation from the plane through the central ring being 0.043 (1) Å. The tert-butyl and benzyl substituents are cis to each other and trans to the N-benzoyl group. The interplanar angle between the aromatic rings of the C-benzyl and N-benzoyl groups is 81.10 (4)°.

Related literature

For background to this class of compound, see: Seebach & Naef (1981 ); Seebach et al. (1984 ); Seebach & Fadel (1985 ). For applications of these compounds in asymmetric synthesis, see: Krall et al. (2005 ); Barry & Rutledge (2008 ); Dungan et al. (2010 , 2012 ). For related structures, see: Dungan et al. (2010); Barry et al. (2012 ).

Experimental

Crystal data

C₂₁H₂₃NO₃
M_r = 337.40
Monoclinic, C 2
a = 23.6627 (17) Å
b = 7.1449 (5) Å
c = 12.2265 (9) Å
β = 117.470 (1)°
V = 1834.0 (2) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 100 K
0.50 × 0.10 × 0.10 mm

Data collection

Bruker D8 platform diffractometer with SMART APEX CCD area detector
Absorption correction: multi-scan (SADABS; Sheldrick, 2000 ) T_min = 0.886, T_max = 0.992
15833 measured reflections
2390 independent reflections
2335 reflections with I > 2σ(I)
R_int = 0.019

Refinement

R[F² > 2σ(F²)] = 0.034
wR(F²) = 0.088
S = 1.05
2390 reflections
229 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.32 e Å⁻³
Δρ_min = −0.19 e Å⁻³

Data collection: SMART (Bruker, 2001 ); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT; 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: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536812035556/kj2203sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812035556/kj2203Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536812035556/kj2203Isup3.cdx

Supporting information file. DOI: 10.1107/S1600536812035556/kj2203Isup4.mol

Supporting information file. DOI: 10.1107/S1600536812035556/kj2203Isup5.cml

checkCIF report

Comment top

The stucture of the title compound (2S,4S)-3-benzoyl-4-benzyl-2-(tert-butyl)oxazolidin-5-one is shown below (Fig. 1). This structure reveals that the oxazolidinone ring is approximately planar, with the tert-butyl and benzyl groups occupying the same face of the ring plane. Observation of the cis isomer is in accord with previously reported NMR experiments (Seebach & Fadel, 1985) and the crystal structures of related compounds (Dungan et al. 2010; Barry et al. 2012). In the crystal, the angle between the oxazolidinone ring and the phenyl ring of the N-benzoyl group (C1 to C6) is 65.74 (4)°, while the angle between the oxazolidinone and the phenyl ring of the C-benzyl group (C16 to C21) is 25.66 (7)°.

Oxazolidinones of this type are of interest due to their capacity to undergo stereoselective α-alkylation via the cyclic enolate, a reaction that exploits the principle of "self-reproduction of chirality centres" introduced by Seebach and co-workers (Seebach & Naef, 1981, Seebach et al., 1984, Seebach & Fadel, 1985). Thus the tert-butyl group directs an incoming electrophile to the opposite face of the planar enolate, giving an enantiopure product with retention of stereochemistry from the original oxazolidinone.

We have recently applied this strategy in the synthesis of ligand architectures designed to mimic the structure and function of non-heme iron enzymes (Krall et al. 2005, Barry & Rutledge, 2008, Dungan et al. 2010, Dungan et al. 2012, Barry et al. 2012)

Related literature top

For background to this class of compound, see: Seebach & Naef (1981); Seebach et al. (1984); Seebach & Fadel (1985). For applications of these compounds in asymmetric synthesis, see: Krall et al. (2005); Barry & Rutledge (2008); Dungan et al. (2010, 2012). For related structures, see: Dungan et al. (2010); Barry et al. (2012).

Experimental top

The title compound was prepared following the procedure reported by Seebach (Seebach & Fadel, 1985). Thus the sodium salt of L-phenylalanine was condensed with pivalaldehyde, by heating at reflux in pentane overnight under Dean-Stark conditions to affect azeotropic removal of water. The intermediate Schiff base thus formed was treated with benzoyl chloride in dichloromethane at 233 K, prompting cyclization to give the crude product. Recrystallization from methanol gave white needles in a low overall yield (31%).

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); 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: SHELXL97 (Sheldrick, 2008).

Figures top

View of (2S,4S)-3-benzoyl-4-benzyl-2-(tert-butyl)oxazolidin-5-one showing displacement ellipsoids at the 50% probability level. Note the cis arrangement of the tert-butyl and benzyl groups.

(2S,4S)-3-Benzoyl-4-benzyl-2-(tert-butyl)-1,3- oxazolidin-5-one top

Crystal data top

C₂₁H₂₃NO₃	F(000) = 720
M_r = 337.40	D_x = 1.222 Mg m⁻³
Monoclinic, C2	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: C 2y	Cell parameters from 9756 reflections
a = 23.6627 (17) Å	θ = 3.0–28.4°
b = 7.1449 (5) Å	µ = 0.08 mm⁻¹
c = 12.2265 (9) Å	T = 100 K
β = 117.470 (1)°	Rod, colourless
V = 1834.0 (2) Å³	0.50 × 0.10 × 0.10 mm
Z = 4

Data collection top

Bruker D8 platform diffractometer SMART APEX CCD area detector	2390 independent reflections
Radiation source: sealed tube	2335 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.019
Detector resolution: 8.366 pixels mm^-1	θ_max = 28.5°, θ_min = 1.9°
ϕ and ω scans	h = −31→31
Absorption correction: multi-scan (SADABS; Sheldrick, 2000)	k = −9→9
T_min = 0.886, T_max = 0.992	l = −16→16
15833 measured reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.034	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.088	H-atom parameters constrained
S = 1.05	w = 1/[σ²(F_o²) + (0.0619P)² + 0.4977P] where P = (F_o² + 2F_c²)/3
2390 reflections	(Δ/σ)_max = 0.005
229 parameters	Δρ_max = 0.32 e Å⁻³
1 restraint	Δρ_min = −0.19 e Å⁻³

Crystal data top

C₂₁H₂₃NO₃	V = 1834.0 (2) Å³
M_r = 337.40	Z = 4
Monoclinic, C2	Mo Kα radiation
a = 23.6627 (17) Å	µ = 0.08 mm⁻¹
b = 7.1449 (5) Å	T = 100 K
c = 12.2265 (9) Å	0.50 × 0.10 × 0.10 mm
β = 117.470 (1)°

Data collection top

Bruker D8 platform diffractometer SMART APEX CCD area detector	2390 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 2000)	2335 reflections with I > 2σ(I)
T_min = 0.886, T_max = 0.992	R_int = 0.019
15833 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.034	1 restraint
wR(F²) = 0.088	H-atom parameters constrained
S = 1.05	Δρ_max = 0.32 e Å⁻³
2390 reflections	Δρ_min = −0.19 e Å⁻³
229 parameters

Special details top

Experimental. R(int) for selected reflections was 0.037 before and 0.019 after correction for absorption. The Ratio of minimum to maximum transmission is 0.893567. The λ/2 correction factor is 0.0015. Friedel pairs were merged.

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 (Å²) top

	x	y	z	U_iso*/U_eq
C1	0.32528 (7)	0.0666 (2)	0.72715 (13)	0.0201 (3)
H1	0.2936	0.1615	0.6991	0.024*
C2	0.35910 (8)	0.0255 (3)	0.85255 (14)	0.0238 (3)
H2	0.3504	0.0929	0.9101	0.029*
C3	0.40519 (8)	−0.1129 (3)	0.89347 (14)	0.0269 (4)
H3	0.4285	−0.1390	0.9791	0.032*
C4	0.41737 (8)	−0.2135 (3)	0.80964 (16)	0.0274 (3)
H4	0.4485	−0.3100	0.8379	0.033*
C5	0.38402 (7)	−0.1736 (2)	0.68398 (15)	0.0232 (3)
H5	0.3924	−0.2422	0.6265	0.028*
C6	0.33832 (7)	−0.0322 (2)	0.64354 (13)	0.0174 (3)
C7	0.29922 (7)	0.0067 (2)	0.50761 (13)	0.0168 (3)
O1	0.24806 (5)	−0.06990 (19)	0.44701 (10)	0.0243 (3)
N	0.32549 (6)	0.12804 (19)	0.45687 (11)	0.0160 (3)
C8	0.28720 (7)	0.1929 (2)	0.32915 (13)	0.0167 (3)
H8	0.2410	0.1878	0.3077	0.020*
C9	0.29772 (7)	0.0885 (2)	0.22984 (13)	0.0186 (3)
C10	0.36825 (7)	0.0743 (3)	0.26437 (15)	0.0248 (3)
H10A	0.3731	0.0156	0.1967	0.037*
H10B	0.3901	−0.0016	0.3391	0.037*
H10C	0.3870	0.2000	0.2795	0.037*
C11	0.26947 (8)	−0.1078 (2)	0.21368 (14)	0.0240 (3)
H11A	0.2922	−0.1782	0.2906	0.036*
H11B	0.2738	−0.1725	0.1472	0.036*
H11C	0.2243	−0.0989	0.1928	0.036*
C12	0.26277 (8)	0.1979 (3)	0.10837 (14)	0.0269 (3)
H12A	0.2636	0.1257	0.0410	0.040*
H12B	0.2840	0.3185	0.1158	0.040*
H12C	0.2185	0.2193	0.0910	0.040*
O2	0.30612 (5)	0.38597 (16)	0.33203 (9)	0.0201 (2)
C13	0.35521 (7)	0.4321 (2)	0.44092 (13)	0.0182 (3)
O3	0.38072 (5)	0.58182 (17)	0.45787 (10)	0.0239 (2)
C14	0.37239 (6)	0.2706 (2)	0.53073 (12)	0.0155 (3)
H14	0.3649	0.3077	0.6019	0.019*
C15	0.44249 (6)	0.2112 (2)	0.57882 (13)	0.0179 (3)
H15A	0.4465	0.0764	0.5999	0.022*
H15B	0.4547	0.2281	0.5121	0.022*
C16	0.48839 (6)	0.3203 (2)	0.69091 (13)	0.0171 (3)
C17	0.49970 (7)	0.2615 (3)	0.80782 (14)	0.0239 (3)
H17	0.4764	0.1590	0.8162	0.029*
C18	0.54481 (8)	0.3517 (3)	0.91234 (15)	0.0301 (4)
H18	0.5519	0.3112	0.9917	0.036*
C19	0.57940 (8)	0.4999 (3)	0.90157 (15)	0.0296 (4)
H19	0.6111	0.5588	0.9733	0.035*
C20	0.56771 (8)	0.5622 (3)	0.78598 (16)	0.0293 (4)
H20	0.5910	0.6653	0.7782	0.035*
C21	0.52189 (7)	0.4739 (2)	0.68114 (14)	0.0224 (3)
H21	0.5134	0.5190	0.6019	0.027*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0200 (6)	0.0198 (7)	0.0207 (7)	0.0012 (6)	0.0096 (5)	0.0004 (6)
C2	0.0277 (8)	0.0263 (8)	0.0187 (7)	−0.0026 (6)	0.0117 (6)	−0.0014 (6)
C3	0.0270 (8)	0.0269 (8)	0.0213 (7)	−0.0038 (7)	0.0064 (6)	0.0055 (6)
C4	0.0262 (8)	0.0199 (8)	0.0313 (8)	0.0045 (6)	0.0093 (7)	0.0049 (7)
C5	0.0244 (7)	0.0191 (7)	0.0261 (7)	0.0007 (6)	0.0116 (6)	−0.0032 (6)
C6	0.0169 (6)	0.0178 (7)	0.0176 (6)	−0.0037 (6)	0.0079 (5)	−0.0013 (5)
C7	0.0169 (6)	0.0185 (7)	0.0164 (6)	−0.0011 (5)	0.0090 (5)	−0.0030 (5)
O1	0.0211 (5)	0.0310 (7)	0.0206 (5)	−0.0092 (5)	0.0095 (4)	−0.0036 (5)
N	0.0146 (5)	0.0178 (6)	0.0139 (5)	−0.0020 (5)	0.0051 (5)	−0.0030 (5)
C8	0.0157 (6)	0.0170 (7)	0.0154 (6)	−0.0014 (5)	0.0054 (5)	−0.0011 (5)
C9	0.0220 (7)	0.0187 (7)	0.0145 (6)	−0.0045 (6)	0.0079 (5)	−0.0022 (5)
C10	0.0254 (7)	0.0278 (8)	0.0247 (7)	−0.0024 (7)	0.0145 (6)	−0.0062 (7)
C11	0.0326 (8)	0.0205 (8)	0.0195 (6)	−0.0074 (7)	0.0124 (6)	−0.0042 (6)
C12	0.0348 (8)	0.0257 (8)	0.0169 (7)	−0.0033 (7)	0.0092 (6)	0.0023 (6)
O2	0.0205 (5)	0.0164 (5)	0.0197 (5)	−0.0009 (4)	0.0062 (4)	−0.0005 (4)
C13	0.0166 (6)	0.0181 (7)	0.0202 (6)	0.0016 (6)	0.0087 (5)	−0.0024 (6)
O3	0.0274 (6)	0.0173 (5)	0.0259 (5)	−0.0038 (5)	0.0113 (5)	−0.0034 (5)
C14	0.0139 (6)	0.0156 (6)	0.0165 (6)	−0.0024 (5)	0.0065 (5)	−0.0036 (5)
C15	0.0139 (6)	0.0188 (7)	0.0199 (6)	−0.0013 (6)	0.0068 (5)	−0.0036 (6)
C16	0.0126 (6)	0.0189 (7)	0.0188 (6)	0.0008 (5)	0.0065 (5)	−0.0024 (6)
C17	0.0189 (7)	0.0296 (8)	0.0223 (7)	0.0001 (6)	0.0087 (6)	0.0039 (7)
C18	0.0253 (7)	0.0419 (11)	0.0186 (7)	0.0069 (8)	0.0062 (6)	0.0013 (7)
C19	0.0207 (7)	0.0327 (9)	0.0250 (7)	0.0024 (7)	0.0017 (6)	−0.0119 (7)
C20	0.0247 (8)	0.0241 (8)	0.0350 (9)	−0.0071 (7)	0.0103 (7)	−0.0082 (8)
C21	0.0225 (7)	0.0222 (8)	0.0227 (7)	−0.0037 (6)	0.0105 (6)	−0.0022 (6)

Geometric parameters (Å, º) top

C1—C6	1.389 (2)	C11—H11A	0.9800
C1—C2	1.395 (2)	C11—H11B	0.9800
C1—H1	0.9500	C11—H11C	0.9800
C2—C3	1.384 (2)	C12—H12A	0.9800
C2—H2	0.9500	C12—H12B	0.9800
C3—C4	1.387 (3)	C12—H12C	0.9800
C3—H3	0.9500	O2—C13	1.3431 (17)
C4—C5	1.395 (2)	C13—O3	1.198 (2)
C4—H4	0.9500	C13—C14	1.514 (2)
C5—C6	1.393 (2)	C14—C15	1.5418 (18)
C5—H5	0.9500	C14—H14	1.0000
C6—C7	1.5090 (19)	C15—C16	1.5141 (19)
C7—O1	1.2194 (18)	C15—H15A	0.9900
C7—N	1.3706 (19)	C15—H15B	0.9900
N—C14	1.4695 (18)	C16—C21	1.391 (2)
N—C8	1.4728 (18)	C16—C17	1.392 (2)
C8—O2	1.4455 (19)	C17—C18	1.389 (2)
C8—C9	1.540 (2)	C17—H17	0.9500
C8—H8	1.0000	C18—C19	1.381 (3)
C9—C10	1.524 (2)	C18—H18	0.9500
C9—C11	1.527 (2)	C19—C20	1.383 (3)
C9—C12	1.539 (2)	C19—H19	0.9500
C10—H10A	0.9800	C20—C21	1.391 (2)
C10—H10B	0.9800	C20—H20	0.9500
C10—H10C	0.9800	C21—H21	0.9500

C6—C1—C2	119.49 (15)	H11A—C11—H11B	109.5
C6—C1—H1	120.3	C9—C11—H11C	109.5
C2—C1—H1	120.3	H11A—C11—H11C	109.5
C3—C2—C1	120.32 (15)	H11B—C11—H11C	109.5
C3—C2—H2	119.8	C9—C12—H12A	109.5
C1—C2—H2	119.8	C9—C12—H12B	109.5
C2—C3—C4	120.08 (14)	H12A—C12—H12B	109.5
C2—C3—H3	120.0	C9—C12—H12C	109.5
C4—C3—H3	120.0	H12A—C12—H12C	109.5
C3—C4—C5	120.20 (15)	H12B—C12—H12C	109.5
C3—C4—H4	119.9	C13—O2—C8	112.03 (12)
C5—C4—H4	119.9	O3—C13—O2	121.81 (14)
C6—C5—C4	119.44 (15)	O3—C13—C14	127.58 (14)
C6—C5—H5	120.3	O2—C13—C14	110.60 (13)
C4—C5—H5	120.3	N—C14—C13	102.04 (11)
C1—C6—C5	120.46 (14)	N—C14—C15	114.74 (12)
C1—C6—C7	119.02 (13)	C13—C14—C15	111.59 (12)
C5—C6—C7	120.39 (13)	N—C14—H14	109.4
O1—C7—N	122.64 (13)	C13—C14—H14	109.4
O1—C7—C6	121.26 (13)	C15—C14—H14	109.4
N—C7—C6	116.08 (12)	C16—C15—C14	113.58 (12)
C7—N—C14	122.12 (12)	C16—C15—H15A	108.9
C7—N—C8	119.56 (12)	C14—C15—H15A	108.9
C14—N—C8	110.75 (12)	C16—C15—H15B	108.9
O2—C8—N	104.03 (11)	C14—C15—H15B	108.9
O2—C8—C9	108.70 (12)	H15A—C15—H15B	107.7
N—C8—C9	116.05 (12)	C21—C16—C17	118.63 (14)
O2—C8—H8	109.3	C21—C16—C15	121.86 (13)
N—C8—H8	109.3	C17—C16—C15	119.45 (14)
C9—C8—H8	109.3	C18—C17—C16	120.44 (16)
C10—C9—C11	109.45 (14)	C18—C17—H17	119.8
C10—C9—C12	109.46 (13)	C16—C17—H17	119.8
C11—C9—C12	109.49 (12)	C19—C18—C17	120.37 (16)
C10—C9—C8	111.61 (12)	C19—C18—H18	119.8
C11—C9—C8	109.08 (12)	C17—C18—H18	119.8
C12—C9—C8	107.72 (13)	C18—C19—C20	119.76 (16)
C9—C10—H10A	109.5	C18—C19—H19	120.1
C9—C10—H10B	109.5	C20—C19—H19	120.1
H10A—C10—H10B	109.5	C19—C20—C21	119.95 (17)
C9—C10—H10C	109.5	C19—C20—H20	120.0
H10A—C10—H10C	109.5	C21—C20—H20	120.0
H10B—C10—H10C	109.5	C16—C21—C20	120.78 (15)
C9—C11—H11A	109.5	C16—C21—H21	119.6
C9—C11—H11B	109.5	C20—C21—H21	119.6

C6—C1—C2—C3	−0.1 (2)	N—C8—C9—C12	−170.29 (12)
C1—C2—C3—C4	−0.9 (3)	N—C8—O2—C13	7.13 (15)
C2—C3—C4—C5	1.1 (3)	C9—C8—O2—C13	−117.09 (13)
C3—C4—C5—C6	−0.2 (3)	C8—O2—C13—O3	174.27 (13)
C2—C1—C6—C5	1.1 (2)	C8—O2—C13—C14	−4.26 (16)
C2—C1—C6—C7	177.00 (14)	C7—N—C14—C13	−144.40 (13)
C4—C5—C6—C1	−0.9 (2)	C8—N—C14—C13	5.00 (14)
C4—C5—C6—C7	−176.77 (15)	C7—N—C14—C15	94.76 (16)
C1—C6—C7—O1	−84.5 (2)	C8—N—C14—C15	−115.84 (13)
C5—C6—C7—O1	91.41 (19)	O3—C13—C14—N	−178.96 (14)
C1—C6—C7—N	97.27 (16)	O2—C13—C14—N	−0.53 (15)
C5—C6—C7—N	−86.80 (18)	O3—C13—C14—C15	−56.0 (2)
O1—C7—N—C14	156.59 (15)	O2—C13—C14—C15	122.48 (13)
C6—C7—N—C14	−25.2 (2)	N—C14—C15—C16	−157.45 (12)
O1—C7—N—C8	9.8 (2)	C13—C14—C15—C16	87.12 (15)
C6—C7—N—C8	−172.04 (13)	C14—C15—C16—C21	−96.99 (16)
C7—N—C8—O2	142.88 (12)	C14—C15—C16—C17	85.79 (17)
C14—N—C8—O2	−7.41 (14)	C21—C16—C17—C18	−1.7 (2)
C7—N—C8—C9	−97.78 (16)	C15—C16—C17—C18	175.60 (15)
C14—N—C8—C9	111.93 (13)	C16—C17—C18—C19	−0.6 (3)
O2—C8—C9—C10	66.66 (16)	C17—C18—C19—C20	1.9 (3)
N—C8—C9—C10	−50.11 (18)	C18—C19—C20—C21	−0.9 (3)
O2—C8—C9—C11	−172.28 (12)	C17—C16—C21—C20	2.7 (2)
N—C8—C9—C11	70.95 (15)	C15—C16—C21—C20	−174.55 (15)
O2—C8—C9—C12	−53.52 (15)	C19—C20—C21—C16	−1.4 (3)

Experimental details

Crystal data
Chemical formula	C₂₁H₂₃NO₃
M_r	337.40
Crystal system, space group	Monoclinic, C2
Temperature (K)	100
a, b, c (Å)	23.6627 (17), 7.1449 (5), 12.2265 (9)
β (°)	117.470 (1)
V (Å³)	1834.0 (2)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.08
Crystal size (mm)	0.50 × 0.10 × 0.10

Data collection
Diffractometer	Bruker D8 platform diffractometer SMART APEX CCD area detector
Absorption correction	Multi-scan (SADABS; Sheldrick, 2000)
T_min, T_max	0.886, 0.992
No. of measured, independent and observed [I > 2σ(I)] reflections	15833, 2390, 2335
R_int	0.019
(sin θ/λ)_max (Å⁻¹)	0.672

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.034, 0.088, 1.05
No. of reflections	2390
No. of parameters	229
No. of restraints	1
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.32, −0.19

Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2001), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Acknowledgements

This work was supported by the University of Sydney and by the School of Chemistry and Chemical Biology and the Centre for Synthesis & Chemical Biology at University College Dublin under the Programme for Research in Third Level Institutions (PRTLI) administered by the HEA.

References

Barry, S. M., Mueller-Bunz, H. & Rutledge, P. J. (2012). Org. Biomol. Chem. doi: 10.1039/C2OB25834J. Google Scholar
Barry, S. M. & Rutledge, P. J. (2008). Synlett, pp. 2172–2174. Google Scholar
Bruker (2001). SAINT and SMART. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Dungan, V. J., Ortin, Y., Mueller-Bunz, H. & Rutledge, P. J. (2010). Org. Biomol. Chem. 8, 1666–1673. Web of Science CSD CrossRef CAS PubMed Google Scholar
Dungan, V. J., Wong, S. M., Barry, S. M. & Rutledge, P. J. (2012). Tetrahedron, 68, 3231–3236. Web of Science CrossRef CAS Google Scholar
Krall, J. A., Rutledge, P. J. & Baldwin, J. E. (2005). Tetrahedron, 61, 137–143. Web of Science CrossRef CAS Google Scholar
Seebach, D. & Fadel, A. (1985). Helv. Chim. Acta, 68, 1243–1250. CrossRef CAS Web of Science Google Scholar
Seebach, D. & Naef, R. (1981). Helv. Chim. Acta, 64, 2704–2708. CrossRef CAS Web of Science Google Scholar
Seebach, D., Naef, R. & Calderari, G. (1984). Tetrahedron, 40, 1313–1324. CrossRef Web of Science Google Scholar
Sheldrick, G. M. (2000). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar