Studies in the furan series. 22. N-Arylfurfuryl- and 5-methylfurfurylamines and their N-allyl derivatives

The Origin of the Halogen Effect on Reactivity and Reversibility of Diels–Alder Cycloadditions Involving Furan

“…[5] Klepo and Jakopcic found that chlorine, bromine, or iodine substituents on furan increase cycloaddition yields and cycloadduct stability (see yields for conversion of 1 to 2). [6] More recently, Padwa and co-workers found that conversions of furanylamides 3 b-d to 5 b-d proceed at higher rates and increased yields than the unsubstituted system 3 a to 5 a (Scheme 1). [7] The possibility that simple halogen substitution might convert previously failed furan cycloadditions into successes caused us to explore the origin and generality of this halogen effect.…”

“…A number of apparently reasonable cycloadditions have been found to be unsuccessful, usually due to substrate inertness [8] or the tendency for products to undergo retrocycloadditions. [9][10][11] A celebrated example is the unattainable direct synthesis of cantharidin (6). [12] Figure 1 illustrates products of failed cycloadditions (8 and 9) as well as lowyielding cycloadditions (10 and 11).…”

Experimental, Monte Carlo and molecular dynamics simulations to investigate corrosion inhibition of mild steel in hydrochloric acid solutions

“…1. All furan derivatives were prepared by sodium borohydride reduction of corresponding azomethynes according to reported procedure (Klepo andJakopi, 1985, 1987;Hansal et al, 1955).…”

“…where A is a proportionality coefficient and n has the meaning of the phase shift, whose value can be considered as a measure of the surface inhomogeneity (Stoynov et al, 1991;Growcock and Jasinski, 1989;Lopez et al, 2003;Rammelt and Reinhard, 1987). The transfer function is thus represented by an equivalent circuit, having only one time constant (Fig.…”

“…The correlation between the inhibitor efficiency and the molecular structure of organic compounds has been extensively investigated (Kuron et al, 1985;Edwards et al, 1994;Sastri and Perumareddi, 1994;Stupniek-Lisac et al, 1995).…”