Domino allylic

Scheme 6/2.23. Rhodium-catalyzed domino allylation/Pause-Khand process...

Scheme 6/4.25. Domino allyl yinyl ether formation/Claisen rearrangement.

A further enantioselective synthesis of (+)-T-4 (125), T-6 (128), T-7 (129) and T-8 (126) has been reported by Stragies and Blechert [198]. Key steps are a Pd-catalyzed domino allylation and a Ru-catalyzed metathesis ring rearrangement. Their strategy represents a general approach towards all naturally occurring tetraponerines and will be illustrated here by the description of the syntheses of (+)-T-4 (125) and (+)-T-8 (126) (Scheme 9). 

The key step is the synthesis of the metathesis precursor, which was required in both the cis- and trans- configurations. The cz .v-configuration was obtained via enantioselective domino allylic alkylations (Scheme 6, 15a and 15b). For the rra/zs-configuation, an allylic alkylation was used to introduce the first amine, but the second amine was introduced via the Mitsunobu reaction25 to achieve an inversion of the stereocentre (Scheme 6,16a and 16b). 

More recently this group has prepared a combination of palladium and cobalt nanoparticles immobilized on silica (PCNS) to form bicyclic enones after domino allylic alkylation-PKR [130]. 

Scheme 2-91. Reductive domino allylic substitution and Pauson-Khand reaction.

Scheme 2-93. Rh-eatalyzed domino allylic substitution/carbocyclizations.

Scheme 2.64 Domino allylic substitution/RCM for the synthesis of cydoalkenes 183.

Scheme 14.20 Tietze s total synthesis of (+)-(R)-pinnatolide (134) via multicomponent domino allylation reaction.

Another example of a domino allylation reaction was published by Cook and Jarugumili [169]. Fe2(CO)g in combination with PPhj has been identified as a low-cost and environmentally benign catalyst system for the allylation of zinc enolates 158 generated in situ from copper-catalyzed asymmetric conjugate addition reactions. This catalyst system provides the allylated products 159 in modest to good yields at room temperature with unprecedented diastereoselectivity in cyclic enone systems (Scheme 12.74). 

S. Lamande-Langle, M. Abarbri, J. Thibonnet, A. Dnchene, J.-L. Parrain, Chem. Commun. 2010,46,5157-5159. Domino allylic amination/Sonogashira/heterocyclisation reactions palladium-catalysed three-component synthesis of pyrroles. 

Guo has reported a domino allylation/cycloisomerization process where the 1,6-enyne 43 is formed in situ, leading to highly functionalized bicyclic heterocycles 44 in high selectivities and good yields (Scheme 5.15) [65],... 

Akiyama and coworkers noticed that treatment of diallylisopropylsilane (108) and a,P-unsaturated ketones with Bp3 OEt2 results in a Michael addition of one of the allyl moieties, followed by an intramolecular allylation onto the P-silyl carbocation intermediate to furnish a domino allylation product, (109) (Equation 65) [68]. 

The Ir complex could catalyze the allylic vinylation and the aUylic amination in the same flask (Scheme 5.34) [34]. This result leads to the discovery of an Ir-catalyzed domino allylic vinylation/intramolecular allylic amination of but-2-ene-l,4-diyl dimethyl dicarbonate. 

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