Nucleophilicity Parameters for Alkyl and Aryl Isocyanides

Abstract

How nucleophilic are isocyanides? The kinetics of the reactions of alkyl and aryl isocyanides with benzhydrylium ions indicate that isocyanides are 10 orders of magnitude less reactive than the cyanide ion and their nucleophilic reactivity is comparable to that of allylsilanes and silyl enol ethers (see the diagram for a comparison of the nucleophilicity N of various isocyanides; Ts=toluene‐4‐sulfonyl).

A catalytic synthesis of dihydrofuran‐3(2H)‐imine skeletons from isocyanides, terminal alkynes, and oxiranes

“…To further explore the reaction generality, the reaction was performed with various isocyanides, and the results are summarized in Table 3. In consistent with previous report, [10] tert-butyl isocyanide (1b) afforded the highest yield (entry 1). The reaction with 2-isocyano-2, 4,4-trimethylpentane (1c) resulted in slightly lower yield (entry 2).…”

Multiple Multicomponent Reactions: Unexplored Substrates, Selective Processes, and Versatile Chemotypes in Biomedicine

“…Using a variety of common aldehydes and isocyanides, the double GBBR adducts 5 a – 5 f (36 %‐95 %, Scheme A) were prepared. The innate selectivity of the aminoazine 1 a was then studied using mixtures of two aldehydes and two isocyanides of distinct reactivity . Although unsymmetrical adducts were detected in over‐statistical ratios, the complexity of the mixtures precluded any practical use (see Supporting Information).…”

A design to prevent floating within the N scale of nucleophilicity

“…The published data18, 19, 22–34, 40 using Eqn (4) provide a different viewpoint, based on electrophilicities; substituent effects on the reactivities of benzhydrylium ions are obtained more directly and precisely, using a nucleophile‐specific (substituent effect) s parameter. The subsequent, indirect evaluation of N from Eqn (4) requires long extrapolations, and could be improved by moving the standard electrophile to lower values of E .…”

“…The subsequent, indirect evaluation of N from Eqn (4) requires long extrapolations, and could be improved by moving the standard electrophile to lower values of E . However, the attractive plots18, 19, 22–34, 40 of data for overlapping reaction series of benzhydrylium ions are not suitable for analysis using the ‘overlap assumption’,17 because the slopes ( s ) using Eqn (4) vary (e.g. Table 7) and so the plots are not parallel.…”