Rearrangement Ficini

This reaction is related to the Claisen Rearrangement, Ficini-Claisen Rearrangement, and Overman Rearrangement. 

In this section, the aliphatic Cope and Claisen rearrangements, as depicted in the transformation of I to 2 in Scheme 2, are discussed, as well as variations of the latter (i.e.. Johnson-Claisen, Ireland-Claisen, Reformatsky Claisen, F.schenmoser-Claisen. Ficini Claisen, and hetero-Claisen rearrangements). When X is oxygen, replacement of Cl and C2 with an aromatic ring... 

Reacting an allylic alcohol with an ynavnine to generate an 0-allyl ketene (EA -acetal results in the Ficini-Claiscn rearrangement.1-53 Reaction of (E)- or (Z)-3a with (V,/V-diethyl-2-(phcnyl-sulfanyl)cthynamine results in low diastcreoselectivity in the formation of 6-(benzyloxy)-A ,A-diethyl-2-(phenylsulfanyl)-3-(trifiuoromethyl)hex-4-enamide (5).34 As is the case for the results in Table 23, the stereoselectivity and chemical yield are better for (E)-3a than for (Z)-3a. 

An example of the formation of an ester of an -4,5-alkenoic acid 164 comes in a synthesis of chrysanthemic acid by Ficini and her group.31 Reduction gives the allylic alcohol 163 and [3,3] Claisen rearrangement with triethyl ortho-acetate gives the product 164 in one step. 

Addition of Alcohols to Ynamines and Ynamides (Ficini-Claisen Rearrangement)... 

Shortly after Meerwein s and Eschenmoser s original reports, Ficini disclosed the use of ynamines as suitable precursors of aUyhc ketene N,0-acetals (Scheme 7.8) [10, 17]. AUyhc alcohols add to ynamines (15) either in the presence of catalytic amounts of a Lewis acid, for instance BFj-OEtj, or at elevated temperatures. This addition presumably proceeds through the intermediacy of a keteniminium ion 16. The resulting ketene N,0-acetals then undergo the sigmatropic rearrangement to yield the corresponding amides. 

Scheme 7.23 illustrates the diastereoselectivities observed under various conditions in the synthesis of 2,3-dimethyl pent-5-enamides from ( )-2-buten-l-ol [11, 14, 25, 26, 47]. The anti isomer usually predominates with the exception of the thermal Ficini-Claisen variant (Scheme 7.23, Eq. 2) [18]. In this case, slow addition of the allylic alcohol to the ynamine at elevated temperatures resulted in a 1 2 mixture of aniv.syn products. This result can be explained by assuming that addition of the alcohol to the ketene iminium intermediate (cf 16, Scheme 7.9) occurs from the less hindered side and results in the preferential formation of the (E)-ketene N,0-acetal. This kinetic intermediate then undergoes rearrangement...

Hsung and co-workers have developed an asymmetric Ficini-Claisen rearrangement which is based on the chiral yanamide 326. In presence of Bronsted acid, yanamide is generated putative ketene iminium species 328 which trapped allylic alcohol to result in formation of. E-ketene aminal. The... 

Ficini-Claisen rearrangement proceeded via the dipole minimized chair-like transition state 329 leading to the major product 327. ... 

Mulder JA, Hsung RP, Frederick MO, Tracey MR, Zificsak CA. The first stereoselective Ficini-Claisen rearrangement using chiral ynamides. Org. Lett. 2002 4(8) 1383-1386. 

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