Ylidenenorbornadienes (YNDs), prepared by [4 + 2] cycloadditions between fulvenes and acetylene carboxylates, react with betamercaptoethanol to yield a mixture of four diastereomers. These four diastereomers fragment via a retro-[4 + 2] cycloaddition at differing rates. A simulated kinetics approach extrapolated the rate constants of the diastereomers from the observed rate data. YNDs display wide variability in rate of fragmentation, dependent on the stereoelectronics of the ylidene substituents. A substrate containing one carboxylic ester proved exceptionally stable to fragmentation.

At elevated temperatures, a strained, cyclic meta-quaterphenylene acetylene undergoes an intramolecular cyclization reaction to form benz[e]indeno [1,2,3-hi]acephenanthrylene. This reaction represents an example of a Diels−Alder reaction at the 2-, 1-, 1′-, and 2′-positions of a biphenyl derivative, a region analogous to the bay regions of perylene and other periacenes. The reaction proceeds cleanly with high conversion. Kinetics studies of a methylated derivative reveal that the ΔG ‡ for the reaction is ∼40− 41 kcal/mol, and computational models predict a similar value of G rel for the transition state of a concerted [4 + 2]-cycloaddition.

Experimental measurements of the thermal effects of the same osmolytes on two different globular proteins, C-reactive protein (CRP) and tumor necrosis factor alpha (TNFα), have shown that quantifying the change...