Synthesis of 4-substituted tetrahydropyridines by cross-coupling of enol phosphates

Iron‐Catalyzed C−O Bond Activation: Opportunity for Sustainable Catalysis

“…[37] In this coupling, [Fe(acac) 3 ]( 3mol %) serves as ac atalysti nT HF at À20 8C, typically in the presence of NMPorDMPU.Intriguingly,the authors demonstrated that enol phosphates acted as ligands to iron in some cases, which obviated the need for NMP or DMPU additives. [38] In this context,e arlier studies on the cross-couplingo fe nol phosphates with alkyl Grignard reagents, to prepareastereodefined olefin in the synthesis of salvinorin Ab yEvans and coworkers (Scheme 15 A), [39] and substituted piperidines by Begtrup and co-workers (Scheme 15 B), [40] further demonstrate the synthetic utility of such transformations. In contrast, the use of [Fe(acac) 3 ]a lone resulted in al ow yield of the coupling product (< 15 %).…”

Iron Catalysis in Organic Synthesis

“…Vinyl phosphates obtained from 4-piperidones have been treated with butylmagnesium bromide in the presence of Fe(acac) 3 to afford 4-butyl-1,2,3,6-tetrahydropyridines in good yields. 295 An application to natural product synthesis has been reported by Evans and co-workers for the synthesis of the k-opioid receptor antagonist salvinorin A (Scheme 137). 296 A broader study on the reaction of vinyl phosphate electrophiles with alkyl and aryl Grignard reagents was subsequently carried out by Cahiez and co-workers (Scheme 138).…”

Transition metals in organic synthesis: Highlights for the year 2005

“…A ferrocenyl boronic acid reagent was coupled with a 1-iodonaphthalene [17]. (9) 2-Iodo-2-ene-1-ones [159], 3-tosyl-2-eneoates [23,160], benzylic carbonates and acetates [161,162], 2-fluorobenzoic acid salts [24], benzylic phosphates [163], 4-tosylphosphacoumarin [164], chloroformates and carbamoyl chlorides [165], bis-alkenylphosphates [166], enol phosphates [167], halo-1-azaazulenes [168] and thioenol ethers [169] were coupled with organoboron reagents. ␤,␤-Dichloroenamides were coupled with organoboron reagents to give ␤-substituted-␤-chloroenamides.…”