4-Chlorobenzoyl-meso-octamethylcalix[2]pyrrolidino[2]pyrrole: an acyl chloride derivative of a partially reduced calix[4] pyrrole

In the title compound, C35H47ClN4O, the two pyrrolidine rings have envelope conformations. The conformation of the macrocycle is stabilized by N—H⋯N hydrogen bonds and a C—H⋯N interaction. The benzoyl ring is inclined to the adjacent pyrrole ring by 11.66 (11)°, with a centroid–centroid distance of 3.7488 (13) Å. In the crystal, molecules are linked by N—H⋯O hydrogen bonds into helical chains propagating in [010] and C—H⋯O and C—H⋯π interactions are also observed.

In the title compound, C 35 H 47 ClN 4 O, the two pyrrolidine rings have envelope conformations. The conformation of the macrocycle is stabilized by N-HÁ Á ÁN hydrogen bonds and a C-HÁ Á ÁN interaction. The benzoyl ring is inclined to the adjacent pyrrole ring by 11.66 (11) , with a centroid-centroid distance of 3.7488 (13) Å . In the crystal, molecules are linked by N-HÁ Á ÁO hydrogen bonds into helical chains propagating in [010] and C-HÁ Á ÁO and C-HÁ Á Á interactions are also observed. H atoms treated by a mixture of independent and constrained refinement Á max = 0.24 e Å À3 Á min = À0.34 e Å À3 Table 1 Hydrogen-bond geometry (Å , ).

Related literature
Cg1 is the centroid of pyrrole ring N2/C3/C4/C25/C26; Cg2 is the centroid of the benzene ring C30-C35.  [Journot et al., 2012a;Zhang et al., 2009]. Herein, we report on the synthesis and crystal structure of the title 4-chlorobenzoyl derivative, one of five compounds that have been studied by X-ray diffraction analysis (Journot et al., 2012b,c,d,e).
In the crystal, molecules are linked via an N-H···O hydrogen bond, involving the N3 pyrrolidine H-atom (H3N) and the benzoyl O atom (O1), leading to the formation of helical chains propagating along [010] -see Fig. 2 and Table 1. The same O atom is involved in a C-H···O contact with methyl group C23. A C-H···π interaction is also observed, involving the methyl group C27 and the benzoyl ring (C30-C35) [see Table 1].
The overall geometry and crystal packing is very similar to that reported for the 4-methoxybenzoyl derivative (Journot Footnote to Table 1: Cg1 is the centroid of pyrrole ring (N2,C3,C4,C25,C26); Cg2 is the centroid of the benzene ring (C30-C35).

Experimental
The general procedure for the N-acylation of meso-octamethylcalix[2]pyrrolidino[2]pyrrole (1) is illustrated in Fig. 3. A two-necked flask fitted with a gas inlet and containing a stirrer bar was charged with 100 mg (0.23 mmol) of meso-octa- (1), 4-chlorobenzoyl chloride (2c) (53.61 µL, 0.48 mmol), potassium carbonate (70 mg, 0.48 mmol) in THF (5 ml) and acetonitrile (2.5 ml). The reaction vessel was flushed with argon and sealed with a septum. After 15 min. a precipitate appeared and the reaction mixture was stirred for 2 h room temperature. 10% sodium carbonate was then added and the reaction mixture was extracted with dichloromethane. The organic layer was washed

Refinement
The NH H-atoms were located in a difference electron-density map. H-atom H3N was freely refined while the other NH H-atoms and the C-bound H-atoms were included in calculated positions and treated as riding atoms: N-H = 0.88 Å, C -H = 0.95 Å for CH-allyl and CH-aromatic H atoms, and 1.00, 0.99 and 0.98 Å, for methine, methylene and methyl H atoms, respectively, with U iso (H) = k × U eq (N,C), where k = 1.5 for CH 3 H-atoms, and 1.2 for the other H-atoms.  A view of the molecular structure of the title compound, with the numbering scheme and displacement ellipsoids drawn at the 50% probability level. The N-H···N hydrogen bonds are shown as dashed lines (see Table 1 Table 1 for details; the C-bound H atoms have been omitted for clarity).

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. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.