Syntheses of novel annelated dihydropyrenes from a common aryne intermediate and interpretation of their proton NMR data

Date

2018-06-19

Authors

Zhou, Pengzu

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Abstract

The existence of the reactive intermediate trans-10b,10c-dimethyl-10b,10c-dihydropyr-1-yne, 57, generated via dehydrobromination, was proved by trapping with N,N-diethyl-1,3-butadienylamine, furan and a series of isoannelated furans. Comparison of 57 with benzyne, 1, was implemented using the results of MMX/PCMODEL calculations. A fast route to annelated dihydropyrenes was developed via the reactive intermediate 57. Through this route, five annelated dihydropyrenes, namely, trans-14b,14c-dimethyl-14b,14c-dihydronaphtho (2,1,8-gra) naphthacene, 204, trans-16b,16c-dimethyl-16b,16c-dihydrobenzo (a) naphtho (2,1,8-fgh) naphthacene, 206a, trans-16b,16c-dimethyl-16b,16c-dihydrobenzo (a) naphtho (2,1,8-hij) naphthacene, 206b, trans-14b,14c,18b,18c-tetramethyl-14b,14c,18b, 18c-tetrahydrodinaphtho (2,1,8-uva; 2,1,8-jkl) pentacene, 224a, and trans-15b,15c,18b,18c-tetramethyl-15b,15c,18b, 18c-tetrahydrodinaphtho (2,1,8-uva; 2,1,8-pon) pentacene, 224b, and one bridged oxa (17) annulene, namely, trans-11b,11c-dimethyl-11b,11c-dihydropyreno (1,2-c) furan, 222, were synthesized. Metal complexation of the benzo (a) dihydropyrene 95 was investigated. This led to the first two metal dihydropyrene complexes, namely, (7,8,9,10,10a,10b-η6)-trans-12b,12c-dimethyl-12b,12c-dihydrobenzo (a) pyrenechromium(0)-tricarbonyl, 239, and (1,2,3,3a-η4) -trans-12b,12c-dimethyl-12b,12c-dihydrobenzo (a) pyreneiron(0)tricarbonyl, 209. The delocalization effects due to complexation were studied. Combining the results of the newly synthesized annelated dihydropyrenes with previously obtained ones, a series of correlations between theoretical calculations and experimental results, such as bond order vs. chemical shift, bond order vs. coupling constant, and ring current vs. chemical shift were devised. The ortho-metalation of dihydropyrene derivatives and synthesis of 1-bromo-2-fluoro-dihydropyrene were attempted. This led to two new dihydropyrene derivatives, namely, trimethylacetamino-trans-10b,10c-dimethyl-10b,10c-dihydropyrene, 99, and 2-diethylcarbamyl-trans-10b,10c-dimethyl-10b,10c-dihydropyrene, 109, and two new cyclophane derivatives, namely, syn-5-bromo-6-fluoro-9,18-dimethyl-2,11-dithia (3.3) metacyclophane, 131a, and anti-5-bromo-6-fluoro-9,18-dimethyl-2,11-dithia (3.3) metacyclophane, 131b.

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Keywords

Benzene, Synthesis, Reactivity, Aromatic compounds

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