Crystal structure of a mono-bridged calix[4]arene.

The title compound, 5(2)-[(5-bromo-pent-yl)-oxy]-1(2),1(14),3(5),5(5)-tetra-tert-butyl-1(7),1(8),1(9),1(10)-tetra-hydro-1(6) H,1(16) H-1(4,12)-dibenzo[b,e][1,7]dioxa-cyclo-dodecina-3,5(1,3)-dibenzena-cyclo-hexa-phan-3(2)-ol, C54H73BrO4, was synthesized from the reaction of tert-butyl-calix[4]arene with 1,5-di-bromo-pentane using K2CO3 in CH3CN. The structure consists of a calixarene unit with a five-carbon bridge connecting two proximal phenolic O atoms, and with a bromo-pent-oxy chain on one of the remaining phenolic O atoms. The calixarene unit was found to have a flattened cone conformation with no solvent (or other guest) mol-ecule observed in the cavity. Two of the opposite phenyl rings lean outwards with fold angles of 136.2 (1) and 133.0 (1)° between the rings and the plane of the bridging methyl-ene C atoms, while the other two opposite rings form fold angles of 83.27 (9) and 105.46 (9)°. There is considerable disorder in this mol-ecule. One of the tert-butyl groups is disordered over two conformations with occupancies of 0.527 (5) and 0.473 (5). The bromo-pent-oxy chain is disordered over three configurations with occupancies of 0.418, 0.332 and 0.250. The five-carbon bridge connecting two proximal phenolic O atoms is disordered over two conformations with occupancies of 0.537 (7) and 0.463 (7).

Calixarene-based mol-ecular capsule from olefin metathesis.

The reaction of tetra-kis-(all-yloxy)calix[4]arene with the first-generation Grubbs catalyst, followed by catalytic hydrogenation, gave the novel bis-calixarene 15,20,46,51,64,69,74,79-octa-oxatridecacyclo[32.28.8.8(3,28).1(13,53).1(22,44).0(9,14).0(21,26).0(38,70).0(40,45).0(52,57).0(59,63).0(7,80).0(32,73)]octa-conta-1(63),3,5,7(80),9(14),10,12,21,23,25,28(73),29,31,34,36,38(70),40,42,44,52,54,56,59,61-tetra-cosa-ene benzene monosolvate, C72H72O8·C6H6. The structure consists of two calix[4]arene units connected by four-carbon chains at each of the four O atoms on their narrow rims, to form a cage. Each of the calix[4]arene units has a flattened cone conformation in which two of the opposite aryl groups are closer together and nearly parallel [dihedral angle between planes = 7.35 (16)°], and the other two aryl groups are splayed outward [dihedral angle between planes = 72.20 (8)°]. While the cavity contains no solvent or other guest mol-ecule, there is benzene solvent mol-ecule in the lattice. Two of the alkyl linking arms were disordered over two conformations with occupancies of 0.582 (3)/0.418 (3) and 0.33 (4)/0.467 (4). They were constrained to have similar metrical and thermal parameters.

3-[1-(4-Bromo-phen-yl)eth-oxy]-2,2,5-trimethyl-4-phenyl-3-aza-hexa-ne.

The title compound, C22H30BrNO, is an alk-oxy-amine compound, an effective initiator in nitroxide-mediated free radical polymerization. It was prepared as a mixture of two diasteromers; the crystal for the X-ray analysis showed one of these as a pair of R,S and S,R enanti-omers. The tert-butyl and isopropyl groups are in an almost anti conformation in the crystal [C-N-C-C torsion angle = -168.8 (1)°], and the methyl group of the ethoxy group is in an approximate anti relationship to the tert-butyl group. The dihedral angle between the phenyl and benzene rings is 33.12 (7)°. The Br atom is disordered over two positions, with occupancies of 0.9139 (16) and 0.0861 (16). In the crystal, weak C-H⋯Br contacts link the mol-ecules into chains along [-110].

A bis-calixarene from olefin metathesis.

A ring-closing olefin metathesis reaction of tetra-kis-(all-yl-oxy)calix[4]arene gave the bis- calixarene, (15E,40E,60E)-65,74-bis-(prop-2-en-1-yl-oxy)-13,18,38,43,58,63-hexa-oxado-deca-cyclo-[28.26.8.7(20,36).1(11,45).1(51,55).0(5,57).0(7,12).0(19,24).0(26,64).0(32,37).0(44,49).1(68,72)]tetra-hepta-conta-1,3,5(57),7,9,11,15,19(24),20,22,26,28,30(64),32,34,36,40,44(49),45,47,51,53,55(65),60,68,70,72(74)-hepta-cosa-ene, C(74)H(68)O(8). It is a cage formed from two calix[4]arene units joined by butenyl groups at three of the O atoms on the narrow rim. The fourth O atom on each calixarene unit is joined with an allyl group. Each of the calix[4]arene units has a flattened cone conformation in which the all-yloxy-substituted aryl group and the opposite aryl group are close together and almost parallel [dihedral angle between planes = 1.09 (11)°], and the other two aryl groups are splayed outward [dihedral angle between planes = 79.53 (11)°]. No guest mol-ecule (e.g. solvent) was observed within the cage. The alkene C atoms of one of the links between the calixarene moieties are disordered over two orientations with occupancies of 0.533 (9) and 0.467 (9).

(3aR,8aR)-2,2,6,6-Tetra-methyl-4,4,8,8-tetra-phenyl-tetra-hydro-1,3-dioxolo[4,5-e][1,3,2]dioxasilepine.

The title compound, C(33)H(34)O(4)Si, is a dioxasilepine compound, an effective chiral dopant for the determination of high helical twisting powers in liquid crystals. Its structure consists of a five-membered dioxolo ring fused to a seven-membered dioxasilepine ring which contains two sets of phenyl rings in a twisted butterfly shape attached to the two Csp(3) atoms in the ring opposite each other. Two methyl groups are attached to the Si atom in the ring and two additional methyl groups are attached to the Csp(3) atom in the dioxolo ring (one of which is disordered) and which lies in an envelope pattern. The dihedral angles between the mean planes of the phenyl ring pairs are 85.9 (2) and 83.5 (1)°. The dihedral angles between the mean planes of the dioxolo ring and the two pairs of butterfly shaped phenyl rings are 46.2 (1), 67.7 (1), 35.6 (7) and 83.5 (1)°.

The Wurtz-Fittig reaction in the preparation of C-silylated calixarenes.

The Wurtz-Fittig reaction of tetraiodo calixarene 3 with Na/Me3SiCl in DME gave a mixture of tetrakis- and tris-silylated calixarenes (6 and 7). Tris(silyl) calixarene 7 was assigned the flattened cone conformation. A model study using p-bromoanisole and p-iodoanisole with Na/Me3SiCl gave the best results with p-bromoanisole in toluene. Attempts to extend this reaction to the tetrabromo calixarene 4 resulted in slow reactions giving mixtures of products. However, the Wurtz-Fittig reaction of the bromo benzyloxycalixarene 5 was faster, giving the debenzylated silyl ether 12.

Calix[4]arenes with siloxanes bridging opposite rings.

Several C-silylated (allyldimethylsilyl) calixarenes (1, 14, and 18) were treated with commercial TBAF in THF, giving the novel calixarenes 2, 15, and 19, in which the opposite rings were bridged by a Si-O-Si siloxane group. Compound 19 and the derived phenol 20 (as well as the dibromocalixarene precursor 17) were mixtures of cone and partial cone conformations according to NMR, while 2 and 15 (as well as 14 and the cone components of 17, 19, and 20) were in flattened cone conformations.

Reactions of (Triphenylsilyl)ethylene Oxide with Grignard Reagents (and with MgBr(2)). A Reinvestigation.

Reactions of (triphenylsilyl)ethylene oxide (1) with simple Grignard reagents such as EtMgBr and PhMgBr have been reported to yield crystalline hydroxysilanes assigned as the alpha-hydroxy silanes expected from beta opening of the epoxide. Reinvestigation of these reactions showed that the hydroxysilanes were the beta-hydroxy silanes 4 and 7 expected from a rearrangement-trapping sequence; a bromohydrin, assigned as the alpha-bromo-beta-hydroxy silane 9 from alpha opening, and (triphenylsilyl)acetaldehyde (8) were also formed.