Synthesis and conformation of [2.2](2,5)furano(2,5)pyridinophane

Synthesis and Properties of Heterophanes

“…The spectrum of compound 95 could not be examined because of its lack of thermal stability. 142 Thus, it appears that the furan ring is tilted so that the oxygen lies closer to the nitrogen side of the pyridine ring. 142 Thus, it appears that the furan ring is tilted so that the oxygen lies closer to the nitrogen side of the pyridine ring.…”

N-(p-Bromophenyl) [2.2] (2,5)pyrrolophane. Synthesis and self-condensation

“…To this end a recently described method of Hiyama et al4a was employed, which permits the stereoselective endo methylation of cyclopropylidenes derived from geminal dibromocyclopropanes. Upon reaction of 9,9dibromo-cis -bicyclo [6.1.0]nonane (1) with butyllithium at -95 °C and subsequent treatment with excess of methyl iodide in THF, the desired 9-exo-bromo-9-endo-methyl-cis-bicyclo [6.1.0] nonane (2) was isolated in essentially quantitative yield. In a similar way, the acetonide of 4,5-irans-dihydroxy-9,9-dibromo-cis -bicyclo [6.1.0] nonane (3) was converted to the corresponding endo-methyl derivative (4) in 92% yield.…”

Cyclophanes. 10. Synthesis and conformational behavior of [2.2](2,5)pyrrolophanes

“…Paal-Knorr Cyclization Route. This successful synthetic approach to the [2.2](2,5)pyrrolophanes is based on work of Nozaki9b and Wasserman108 in which the former synthesized [8] (2,5)pyrrolophane (7) by cyclization of 1,4-cyclododecadione with ammonia (see Scheme II) and the latter synthesized N-methyl-3,6-diketo [8]pyrrolophane (8) and N,N'- cyclization was potentially available from the furan containing phanes by hydrolysis, a series of mixed [2.2] (2,5)pyrrolophanes was synthesized initially.…”

“…A. Pyrrolophanes from 3,6-Diketo [8]phanes. In general, the synthetic scheme (see Scheme IV) involved 7-diketone 10 from the appropriate furanophane 9 by acid hydrolysis in the absence of light and oxygen.…”

“…In general, the synthetic scheme (see Scheme IV) involved 7-diketone 10 from the appropriate furanophane 9 by acid hydrolysis in the absence of light and oxygen. The crystalline diketones were then cyclized to the pyrrolophanes by treatment with ammonia via a Paal-Knorr reaction.118 Thus 3.6-diketo [8] (1,4) naphthalenophane (10b) and 3,6-diketo[8] -(2.5) furanophane (10c) were synthesized in 71 and 68% yield, respectively, as had been done previously by Cram5b for 3.6diketo [8]paracyclophane (10a), by refluxing 9b and 9c, respectively, for 18 h at 105 °C and 17 h at 55 °C in an acetic acid/water/sulfuric acid medium. Treatment of 10a, 10b, and 10c with ammonia in acetic acid at 80 °C in the dark under nitrogen followed by workup and chromatography afforded pyrrolophanes 11a, 12a, and 13a in 55,86, and 67% yields, respectively.…”