Palladium-catalyzed 1,3-oxygen-to-carbon alkyl shifts. Basic studies

Metal catalyzed allylic alkylation: its development in the Trost laboratories

“…On the other hand, subjecting the enol vinylogous ester to Pd(0) in DMSO at 120°C effected O to C rearrangement to the cyclopentanones favoring the Z geometry. 23 An alternative synthesis of the enol vinylogous ester by conjugate addition of an alcohol onto an ynoate followed by Pd catalyzed O to C isomerization provided ready access to prostanoids (eq 20). With a non-β-keto ester as the pro-nucleophile, typical cyclization by C-C bond formation occurs (eq 21).…”

Catalytic palladium-oxyallyl cycloaddition

“…4A), as the b-keto ester anion is weakly basic, well-stabilized, and thus a good leaving group for the palladium p-allyl formation. Therefore, we anticipated that an isomerization reaction from the tetrahydrofuran 21 to more thermodynamically stable cyclopentanone 22 via intermediate 14 should be feasible by using palladium catalysts that can facilitate the irreversible C-C bond reductive elimination (27)(28)(29). Indeed, the desired [1,3] O-to-C rearrangement of cycloaddition products from linear dienes was found to proceed and afford a,b-disubstituted cyclopentanones (22a to 22d) using CpPd(cinnamyl)/1,2-bis(diphenylphosphino)ethane (dppe) as the catalyst under elevated temperature.…”

Synthesis and palladium-catalysed isomerisation of fused polycyclic tetrahydrofurans: efficient and stereoselective one-pot domino construction of functionalised bridged bicyclo[n.2.1] ring systems

“…As previously described [23], the condensation promoted by K 2 CO 3 in refluxing THF between easily available cyclic 1,3-diactivated ketones and trans-1,4-dibromobutene allows the one-pot construction of 2-vinyl-hexahydro-2,3benzofuran derivatives, which are obtained with very high chemical purity after a simple filtration through a short pad of celite. On the basis of work by Tsuji [27] and Trost [28], we thought that these polycyclic enol ethers, from the five-to seven-membered ring series, could be involved in a palladium-catalysed rearrangement leading to highly functionalised bicyclo[n.…”

“…The latter compounds, containing a 2-vinyl-or 2-vinylidene function, are known to undergo a variety of rearrangements including thermal [24][25][26] or palladiumcatalysed [27][28][29]…”