148873-79-4

Upstream product

• 110-88-3 1,3,5-Trioxan 
• 27129-86-8 1-bromomethyl-3,5-dimethylbenzene 
• 52850-48-3 2,6-Dimethyl-terephthaloyl dichloride 
• 80238-12-6 2,6-dimethyl-terephthalic acid 
• 157248-87-8 1,4-Bis(hydroxymethyl)-2,6-dimethylbenzene 

Downstream Products

• 148873-80-7 1,4-bis(mercaptomethyl)-2,6-dimethylbenzene 

Relevant academic research and scientific papers

Conformational Studies of Selectively Methylated (1,3)(1,4)Cyclophanes. Steric Effects in the Relative Conformational Ground States

Three selectively methylated (1,3)(1,4)cyclophanes, namely, 12,15-dimethyl-, 12,16-dimethyl-, and 12,13,14,15-tetramethyl(1,3)(1,4)cyclophanes, were synthesized from their corresponding dithia(1,3)(1,4)cyclophanes by the photochemical desulfurization method.Dynamic 1H NMR spectroscopy was employed to estimate the relative conformational barrier in each cyclophane.The results show that there is an increase of about 13 kJ mol-1 going from the parent (1,3)(1,4)cyclophane to its 12,15- and 12,16-dimethyl derivatives.This is consistent with the fact that the presence of the methyl substituents increases the relative conformational ground-state energy more than it would affect the transition-state energy.The conformational barrier of the 12,13,15,16-tetramethyl derivative was unexpectedly found to be similar to those at the two dimethylated derivatives.This however could be explained by a decrease in the transition-state energy due to inward bending of the (1,4)-bridged ring accompanied by a decrease in conformational ground-state energy due to outward bending of the methyl groups.

Synthesis and Diatropicity of a trans-10c-Methyl-10b,10c-dihydropyrene-containing Cyclophane: a Novel Aromatic Molecule with a (1,3)Cyclophane within the ?-Cloud of a Annulene

1,4-Bis(bromomethyl)-2,6-dimethylbenzene (17) was obtained by direct bromomethylation of α-bromomesitylene and used for the preparation of 14,18-dimethyl-2,11-dithia(1,3)(1,4)-cyclophane (19).Desulfurization of 19 to afford 12,16-dimethyl(1,4)cyclophane (22) could be achieved via two routes.Selective bromination of the methyl groups in 22 followed by coupling with 2,6-bis(mercaptomethyl)toluene led to the double-layered anti-dithiacyclophane 26.Ring contraction via a Wittig rearrangement-Hofmann elimination sequence gave the double-layered cyclophanediene 14 which underwent valence isomerization to afford the title compound 15.A diatropicity study of 15 suggests that it retains 99percent of the ring current of the parent system 1.Protons of the methylene group directly attached to the dihydropyrene moiety in 15 are, however, shifted about 1 ppm downfield compared with those of the corresponding methylene protons in related dihydropyrenes with internal butyl and but-4-enyl groups.This is attributed to a deviation of the methylene carbon concerned in 15 from the central axis of delocalization of the aromatic ?-cloud in the dihydropyrene.