Electron transfer processes. 36. Carbon-carbon bond scission in an aliphatic SRN reaction

Abstract

We have examined the photostimulated reactions of the nitrocyclopropane 1 with several nucleophiles. We have H Me-C-CH2-C-C(Me)2N02 N02 COCHj 2

Nucleophilic Substitution Reactions by Electron Transfer

“…In all of these ET reactions there is no opening of the cyclopropane ring. However, rearrangement occurs in the reaction of the following cyclopropane substituted by EWG with - CMe 2 NO 2 ions (eq 57) …”

“…However, rearrangement occurs in the reaction of the following cyclopropane substituted by EWG with -CMe 2 NO 2 ions (eq 57). 383 The radical anion of the substrate cleaves into a distonic radical anion, which couples with the Nuto give the radical dianion of the product, responsible for the continuation of the propagation cycle (eq 58).…”

Cooperative Electron Transfer Fragmentation Reactions. Amplification of a Photoreaction through A Tandem Chain Fragmentation of Acceptor and Donor Pinacols

“…Photofragmentation reactions occurring as a consequence of activation by oxidation or reduction of excited states have been observed for a variety of organic molecules, especially for donors such as amines, pinacols, and substituted diarylethanes. − In many cases the fragmentation of the ion radical produces a stable (even-electron) product and a redox active radical. , As a typical example, the cation radicals of electron-rich pinacols such as 1 (KHKH) generate a ketone, K, and the relatively strong reducing ketyl radical, KH • (eq 1). − In previous studies, we have explored subsequent reactions of the photogenerated radicals with reagents such as organic halides. − In the present investigations, we have synthesized and studied electron-deficient pinacols such as 2 (A 2 2+ ) and find that these undergo parallel fragmentations upon one-electron reduction to generate a stable reduced product (AH + ) and a moderately strong oxidizing radical, A •+ (eq 2). Herein we report a cofragmentation which occurs when the two substrates are combined such that tandem chain-propagating redox reactions of the two radicals display a remarkable amplification of an initial photoinduced electron-transfer process.…”

Free radical chain reactions involving an electron transfer process

“…Table 12 seem to indicate that flt-nitro radical derived from the radical anion of 2-bromo-2-nitropropane is trapped by an excess of cyanide ion (Scheme 17). The fragmentation of the resulting radical anion to 2-cyano-2-propyl radical has been previously documented [24]. The formation of 2-cyano-2,3dimethyl-3-nitrobutane 37 occurs by the subsequent coupling of the 2-nitro-2-propyl anion with the 2-cyano-2-propyl radical.…”

“…Another example of the Sp^l process that has been investigated involves carbon-carbon bond scission in the nitrocyclopropane _1 upon reaction with the 2-nitro-2-propyl anion to form 2_ [24]. The reaction apparently proceeds by the Spjjl sequence as shown Scheme 5.…”