Effective Acceleration of Atom Transfer Carbonylation of Alkyl Iodides by Metal Complexes. Application to the Synthesis of the Hinokinin Precursor and Dihydrocapsaicin

Abstract

[reaction: see text] Atom transfer carbonylation (ATC) of alkyl iodides leading to carboxylic acid esters is effectively accelerated by Pd(PPh(3))(4) and Mn(2)(CO)(10) under photoirradiation conditions. In the presence of amines, Pd(0) complexes affected double carbonylations leading to alpha-keto amides, whereas Mn(2)(CO)(10) accelerated only a single carbonylation reaction leading to the corresponding amides. The Pd(0)-accelerated ATC system was successfully applied to the synthesis of hinokinin and dihydrocapsaicin.

Free‐Radical Multicomponent Processes

“…Using alkenols, a straightforward access to lactones is also possible as illustrated by the 3CR between 4, olefin 97, and CO, which produces lactone 98 in good yield (3). Finally, when amines are added as the nucleophile, mono-and dicarbonylated products 99 and 100 are obtained (4) [67]. This strongly suggests the intermediacy of an acyl carbamoyl palladium complex in this reaction, as double carbonylation is rarely observed under radical conditions.…”

“…For instance, addition of octyl iodide 85 onto CO in the presence of ethanol was shown to provide in 16 h the desired ester 94 in 87% yield (Scheme 14.22, (1)) [67]. When the Pd catalyst was omitted, 94 was obtained in only 50% yield after 50 h. With α-iodoester 4, the generated electrophilic radical can add to an electron-rich olefin to generate a new nucleophilic radical that is then trapped by carbon monoxide [68].…”

Natural and Synthetic Alkamides

“…Since its discovery, several studies have been focused on the design and generation of more potent and effective capsaicinoids with less or without pungent action and less toxic effects than capsaicin to be used as analgesics. Several chemical synthesis of capsaicin and analogs have been reported, mainly by amidation of vanillylamine with fatty acid derivatives [115][116][117][118][119][120][121][122][123][124][125][126][127][128][129][130]. Several chemical synthesis of capsaicin and analogs have been reported, mainly by amidation of vanillylamine with fatty acid derivatives [115][116][117][118][119][120][121][122][123][124][125][126][127][128][129][130].…”

Radicals in organic synthesis. Part 1

“…This limitation can be somewhat mitigated by effecting the reaction under palladium(0) or dimanganese decacarbonyl/irradiation conditions. 293 A comparison of the efficiency of the conversion of a secondary iodide 453 into an ester 454 under the different reaction conditions, i.e., no metal catalyst, palladium(0) catalysis and dimanganese decacarbonyl catalysis, is shown in Scheme 141. Whilst the carbonylation of secondary iodides occurs in the absence of a metal, as indicated by the formation of 454 (40%), the reaction is greatly accelerated by both metals.…”