Palladium-Catalyzed Direct Synthesis of Phenanthridones from Benzamides through Tandem N–H/C–H Arylation
We report a palladium-catalyzed method for the direct synthesis of phenanthridones from benzamides in a single step. Unlike previous reports, the current protocol does not need any directing groups or any harsh conditions. This methodology has a wide functional group tolerance therefore a series of phenanthridones were synthesized with a yield up to 87 %. The efficacy of this protocol was further explored by synthesizing some important naturally occurring amaryllidaceae alkaloids in a single step with very good yields.
Practical Synthesis of Phenanthridinones by Palladium-Catalyzed One-Pot C-C and C-N Coupling Reaction: Extending the Substrate Scope to o-Chlorobenzamides
A highly efficient construction of phenanthridinone derivatives from o-halobenzamides was developed by using a phosphine-free palladium catalyst in N,N-dimethylacetamide. The domino reaction proceeds through a sequential C-C and C-N bond-formation process in one pot. This protocol exhibits broad substrate scope and affords a series of phenanthridinones in up to 93 % yield. Importantly, the protocol could also be applied for the less reactive o-chlorobenzamides. The approach constitutes the first example of the synthesis of phenanthridinones from this kind of substrate. Moreover, the success of a gram-scale reaction demonstrated that this operationally simple process is scalable.
Isotope Effects on Hydride Transfer between NAD+ Analogues
Primary kinetic hydrogen isotope effects (KIE's) for hydride transfer between NAD+ analogues are between 6 and 4, for reactions with equilibrium constants ranging from 0.7 to 1016.There is no sign of the sharp change in KIE which would signal the change of a rate-limiting step in a multistep mechanism, and other evidence also indicates a one-step mechanism. 2 The secondary KIE produced by changing the hydrogen already attached at the acceptor site from H to D is about 10percent smaller when the transferred atom is D than when it is H.These results, combined with the values of the primary KIE's, strongly suggest some nuclear tunneling in the reaction coordinate.
Ostovic, Drazen,Roberts, Roger M. G.,Kreevoy, Mourice M.
p. 7629 - 7631
(2007/10/02)
More Articles about upstream products of 87861-98-1