Claisen cascade rearrangement

A benzyl Claisen cascade rearrangement of keteniminium salts leads to a-arylated lactones in the presence of Tf20, collidine (Scheme 14). ... 

Kirsch et al. reported that vinyl propargyl ethers 36 could be converted into the densely substituted furans 38 via the Au(I)-catalyzed cycloisomerization reaction (Scheme 8.17) [125] A variety of substituted furans 38 (Table 8.1) could be obtained under very mild reaction conditions at only 2 mol% catalyst loading. It is believed that this cascade process begins vith the Au(I)-catalyzed Claisen-type rearrangement of 36 leading to the formation of skipped allenyl ketone 37, vhich, upon the Au(I)-catalyzed 5-exo-dig-cyclization, provides furan 38. 

An uncatalyzed amination/aza-Claisen rearrangement/cyclization cascade described by Majumdar et al. was terminated by a final six-membered ring for-... 

Scheme 7.39. Demonstration of the synthetic utility of electrocyclization/Ireland-Claisen rearrangement cascade reaction.

In K.C. Nicolaou s biomimetic synthesis of 1-O-methylforbesione, the construction of the 4-oxatricyclo[4.3.1.0]decan-2-one framework was achieved by using a double Claisen rearrangement that was followed by an intramolecular Diels-Alder reactionJ This one-pot biomimetic double Claisen rearrangement/intramolecular Diels-Alder reaction cascade afforded the natural product in 63% yield. 

Nicolaou, K. C., Li, J. "Biomimetic" cascade reactions in organic synthesis construction of 4-oxatricyclo[4.3.1.0]decan-2-one systems and total synthesis of 1-O-methylforbesione via tandem Claisen rearrangement/Diels-Alder reactions. Angew. Chem.. Int. Ed. Engl. 2001,40, 42644268. 

Scheme 24 Cascade Claisen rearrangement installing the vicinal tertiary and quaternary carbons...

With the preparation of racemic drhydroisocodeine (79), Chida reported a formal synthesis of morphine [52], The synthesis is based on a cascade of sequential Claisen rearrangements of an allylic vicinal diol derivative as key steps. The Claisen rearrangement protocol, as an efficient strategy for the installation of the C13 quaternary carbon, was successfully employed in the preparation of the Amaryllidaceae alkaloid galanthamine, published 1 year before the synthesis of dihydroisocodeinone [64],... 

Tanunoto H, Saito R, Chida N (2008) Formal synthesis of (—)-morphine from D-glucal based on the cascade Claisen rearrangement. Tetrahedron Lett 49 358-362... 

JCS(P1)680>. A gas-phase cascade reaction was applied to the synthesis of 2,7-bis(benzo[b]furan) from the phosphonium ylide illustrated below. A plausible reaction sequence, starting with a Claisen rearrangement, has been proposed <01SL228>. 

Scheme 5 Cascade reaction consisting of propargyl Claisen rearrangement and cyclocondensation.

Scheme 20 2H-Pyrans synthesized by propargyl Claisen rearrangement/isomerization cascade.

P.S., and Tilve, S.G. (2009) Cascade wittig reaction-double claisen and cope rearrangements one-pot synthesis of diprenylated coumarins gravelliferone, balsamiferone, and 6,8-diphenylumbelliferone. Tetrahedron Lett, 50,6488-6490. 

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