Palladium-catalysed inter- and intramolecular formation of C–O bonds from allenes

Abstract

The Pd-catalysed formation of a C-O bond from allenes mainly occurs via the inter- or intramolecular reaction with a hydroxyl group belonging to an alcohol, a phenol or an acid. A carbonyl or a carbonate entity can also be involved. In most cases, the formation of the C-O bond is one step of a domino reaction leading also to a C-C or C-N bond, or to another C-O bond. Thus, a wide range of products, in particular highly functionalized heterocycles, have been synthesised. Catalytic cycles have been proposed but the mechanisms often remain speculative.

Catalytic CH Bond Addition of Pyridines to Allenes by a Rare‐Earth Catalyst

“…In principle, the catalytic CÀHa ddition of pyridines to aC = C double bond of allenes [4] could serve as an efficient and atomeconomical route for the synthesiso fa lkenylated pyridine derivatives. However,such catalytic CÀHalkenylation of apyridine compound with an allene unit has not been reported previously,a lthough al arge number of examples of allene insertion into aromatic CÀHb onds are known.…”

Manganese(I)‐Catalyzed C−H Activation/Diels–Alder/retro‐Diels–Alder Domino Alkyne Annulation featuring Transformable Pyridines

“…[11] Within our program on sustainable CÀHa ctivation, [12] we have now developed am anganese(I)-catalyzed [13,14] C À Ha ctivation/Diels-Alder/retro-Diels-Alder domino strategy (Figure 1). Salient features of our findings include 1) manganese-catalyzed dehydrocyanative domino CÀHa ctivation, 2) CÀHa llenylation [15,16] of pyridones [17] by using transformable pyridyl groups,and 3) the merger of CÀH activation with two pericyclic transformations for complexityincreasing syntheses of bioactive [18] indolone alkaloid derivatives.At the outset of our studies,weprobed the effect exerted by representative bases,a dditives,a nd solvents on the envisioned CÀHa nnulation of pyridone 1a with propargylic carbonate 2a (Table 1a nd Table S1 in the Supporting Information). [19] Based on the results,t he desired CÀH transformation was put into practice with NaOAc as the base,with BPh 3 as the additive (entries 1-6) and MnBr(CO) 5 as the catalyst of choice (entries 7-9).…”

“…[11] Within our program on sustainable CÀHa ctivation, [12] we have now developed am anganese(I)-catalyzed [13,14] C À Ha ctivation/Diels-Alder/retro-Diels-Alder domino strategy (Figure 1). Salient features of our findings include 1) manganese-catalyzed dehydrocyanative domino CÀHa ctivation, 2) CÀHa llenylation [15,16] of pyridones [17] by using transformable pyridyl groups,and 3) the merger of CÀH activation with two pericyclic transformations for complexityincreasing syntheses of bioactive [18] indolone alkaloid derivatives.…”

Solvent-Controlled Switching of Cycloisomerization to Transposition in the Ag/Cu-Promoted Reaction of Terminal α-Allenols

“…Transition-metal catalyzed nucleophile addition to allene group is a very useful tool for the synthesis of functionalized molecules containing heteroatoms in an atom efficient manner [4][5][6][7][8][9]. This reactivity has a benefit because of regiochemistry can be controlled using different metals or changing the substituents or the length of the chain between allene and heteroatom in the intramolecular case.…”