K. L. Evans

Molecules for intramolecular recognition. Synthesis and structures of diaryl- and arylnaphthylethynes

Abstract While synthesizing models for intramolecular recognition, a simple and efficient method for forming terminal arylethynes was developed and palladium-catalyzed coupling chemistry of alkynes with either aryl iodides or aryl triflates was used to form crowded disubstituted alkynes.

Molecules for intramolecular recognition. 2. Synthesis and structures of dinaphthyl- and arylnaphthylethynes.

Three new tetrasubstituted diaryl alkynes have been prepared via palladium-catalyzed coupling of aromatic alkynes with aryl iodides. These molecules show strong absorption and fluorescence. Single crystal X-ray analysis reveals that the rings are on parallel planes.

Lactonization Products of 2-[(2,6-Dimethoxyphenyl)ethynyl]-3-methoxybenzoic Acid

Structural analyses of 2-[(2,6-dimethoxyphenyl)ethynyl]-3-methoxybenzoic acid, (1), and the two products of lactonization, 3-(2,6-dimethoxyphenyl)-5-methoxy-1H-2-benzopyran-1-one, (2), and (Z)-3-[(2,6-dimethoxyphenyl)methylene]-4-methoxy-1(3H)-isobenzofuranone, (3), three isomers of C 18 H 16 O 5 , suggest an explanation for the favored pathway for lactonization. The two rings in (1) form a dihedral angle of 84.30 (4)°. The carboxy group is nearly coplanar with the benzoate ring with an O=C-C-C torsion angle of −3.7 (2)°. The triple-bond length is 1.191 (2) A and the bond angles at the ethynyl C atoms are 176.4 (1) and 171.0 (1)°, both significantly distorted from 180°. The benzopyran ring and the dimethoxyphenyl ring in (2) form a dihedral angle of 58.90 (5)°. The pyrano C=C double-bond length is 1.324 (2) A. Distortions appear in the two exocyclic angles [112.1 (1) and 127.3 (2)°] about the aryl substituted pyrano C atom. The isobenzofuran ring and the dimethoxyphenyl ring in (3) form a dihedral angle of 120.83 (5)°. The exocyclic C=C double-bond length is 1.323 (2) A. Distortions appear in the benzenoid angles at the C atoms adjacent to the ring fusion [117.5 (1) and 116.7 (1)°] and in two of the three angles [121.2 (1), 131.0() (9) and 107.7 (1)°] about the furano C atom of the exocyclic C=C double bond

1-(1-Chlorovinyl)-2,7-dimethoxynaphthalene

C14H13ClO2, Mr = 248.71, monoclinic, P21/n, a = 11.291 (1), b = 7.343 (1), c = 15.223 (2) A, beta = 90.899 (8) degrees, V = 1262.0 (5) A3, Z = 4, Dx = 1.309 g cm-3, lambda(CU K alpha) = 1.54184 A, mu = 26.0 cm-1, F(000) = 520, T = 299 K, R = 0.041 for 2405 observations (of 2516 unique data). The average deviation from planarity is 0.019 (2) A with a maximum of 0.035 (1) A for the fused rings. The dihedral angle between the naphthalene system and the chlorovinyl group is 101.93 (4) degrees. The methoxy group ortho to the chlorovinyl adopts a conformation with the methyl group anti to the neighboring alpha carbon of the ring, with a C-C-O-C torsion angle of -175.6 (2) degrees. The other methoxy group has the methyl syn to the neighboring alpha carbon, with a C-C-O-C torsion angle of 1.9 (3) degrees.

1‐Chloro‐3‐ethynyl‐2,4‐dimethoxybenzene

C10H9ClO2, Mr = 196.6, monoclinic, P2(1)/c, a = 10.8146 (6), b = 8.8883 (8), c = 10.4110 (9) A, beta = 103.101 (6) degrees, V = 974.7 (3) A3, Z = 4, Dx = 1.340 g cm-3, lambda(Cu K alpha) = 1.54184 A, mu = 32.27 cm-1, F(000) = 408, T = 296 K, R = 0.061 for 1405 observations (of 2004 unique data). The molecule contains two methoxy groups; one is nearly coplanar with the benzenoid ring, with C-C-O-C torsion angle -5.2 (5) degrees, and the other, which resides between the chloro and the ethynyl groups, is nearly orthogonal, with the corresponding torsion angle 86.5 (4) degrees. The coplanar methoxy has an angle about O of 118.3 (2) degrees and the orthogonal, 114.7 (1) degrees. The O-CH3 distance in the coplanar methoxy is 1.426 (2) A compared to 1.439 (2) A in the orthogonal. The six-membered ring is planar, with maximum deviation 0.008 (3) A. The C-Cl distance is 1.734 (2) A, and the triple-bond distance is 1.179 (3) A. The ethynyl group forms a nearly linear C-H...O contact with the O atom of the orthogonal methoxy on a glide-related molecule, having C...O distance 3.293 (3) A and angle at H of 167 (3) degrees.