Rearrangements in the synthesis

Scheme 1.41. Cationic domino rearrangement in the synthesis of the 1/-/-cyclopenta[c]carbazole framework.

Fig. 11 Furanose/piperidine rearrangement in the synthesis of 6-oxanortropane glycomimetics.

Thio-Claisen Rearrangement in the Synthesis of Sulfur-containing Heterocyclic Compounds A. V. Anisimov and E. A. Viktorova, Khim. Geterotsikl. Soedin., 1980, 435-449. 

Ferris JP, Orgel LE. An unusual photochemical rearrangement in the synthesis of adenine from hydrogen cyanide. J Am Chem Soc 1966 88 1074. 

Scheme 16 The neophylic rearrangement in the synthesis of 3-aryl piperidines...

Aza-Cope rearrangement in the synthesis and transformations of N-heterocycles 87UK814. 

Pluta and coworkers [ 172,173] reported application of a S - S rearrangement in the synthesis of various complex quinoline derivatives. This work is illustrated by rearrangement of the dithiine 420 (Scheme 133). Treatment of 420 with sodiiun alkanethiolates in DMF or DMSO provided the respective substitution product 421, that rearranged on heating to give 422 and, after methylation, 423. 

C. Blonski and co-workers utilized the Amadori rearrangement in the synthesis of various D-fructose analogs that were modified at C1, C2, or C6 positions. The key intermediate, 1-deoxy-1-toluidinofructose, was obtained from D-glucose quantitatively by reacting D-glucose with p-toluidine in acetic acid. 

Nowicki, J. Claisen, Cope and related rearrangements in the synthesis of flavor and fragrance compounds. Molecules [online computer file] 2000, 5, 1033-1050. 

Acetone- or acetophenone-sensitized irradiation of the enones yields the reeurranged ketones (213, 214) which are described as useful substrates for the synthesis of polyquinane natural products. The enones (215) can be converted by photosensitized irradiation into the diquinanediones (216). Irradiation of (215) in acetone gives a low yield of the tricyclic ketone (217). This ketone, while stable in the dark, is photochemically converted into the diquinanedione (215). The authors present evidence that this conversion results from fission of the cyclopropyl bond to yield the biradical (218). Demuth and Hinsken have reported the use of the oxardi-ir-methane rearrangement in the synthesis of annelated triquinanes. Thus the photo conversion of the enone (219) affords the tetracyclic ketone (220,72%). In an analogous reaction the enone (221) is converted into the isomeric ketone (222,70%). ... 

This section includes, as well as a survey of Beckmann rearrangements in the synthesis of nine-membered rings, miscellaneous ring enlargement reactions involving a 1,2-shift in the ring expansion step. 

In many 1,3-dipolar cycloaddition reactions, the initially formed stereo-genic center(s) will be destroyed in the following rearrangement. In the synthesis of 6,7-di-epz-castanospermine (55) from 53, the aziridine 54 was obtained as the sole product stereoisomer (Scheme 9) [33]. 

Graybill TL, Casillas EG, Pal K, Townsend CA (1999) Silyl Triflate-Mediated Ring-Closure and Rearrangement in the Synthesis of Potential Bisfiiran-Containing Intermediates of Aflatoxin Biosynthesis. J Am Chem Soc 121 7729... 

Scheme 18.30 Diastereoselective Mislow-Evans rearrangement in the synthesis of gabosine carhasugars. ...

Although nitrogen ylides have been extensively used in organic transformations, especially those concerning the formation of nitrogen heterocycles,not many references are available for the use aza-sulfonium ylides and the Sommelet-Hauser rearrangement in the synthesis of indole derivatives. 

Knight et al. employed a related rearrangement in the synthesis of (-)-a-kainic acid (Scheme4.100). The lactone starting material is derived from L-aspartic acid (92). 

Ireland recognized early on the potential for the Claisen rearrangement in the synthesis of furan and pyran containing natural products. In 1980 Ireland and Vevert published the syntheses of both (-)- and (+)-nonactic acid using the Claisen rearrangement to establish the C2,C3 stereocenters (Scheme 4.111). Rearrangement of the S-silyl ketene acetal via the boat transition state afforded the methyl ester with an 86 14 diastereoselectivity [104]. 

Corey et al. used the asymmetric Ireland-Claisen rearrangement in the synthesis of j8-elemene (Scheme 4.131) [124], Rearrangement of the Z-(0)-B-ketene acetal via the chair transition state afforded the trienic acid in good yield with complete diastereo- and enantioselectivity. 

Following his impressive illustration of the usefulness of the orthoester Claisen rearrangement in the synthesis of squalene [7], Johnson [66] used this reaction thoroughly in several biomimetic syntheses of steroids. Some examples of these reactions are depicted in Scheme 6.47. Esters were generally obtained in high yield with complete stereoselectivity. 

Scheme 7.25 The Eschenmoser-Claisen rearrangement in the synthesis of morphine alkaloids.

In 1980, Tanabe and Hayashi successfully used the Carroll rearrangement in the synthesis of cholesterol and its C-20epimeric diastereomer, 20-isocholesterol, from the readily available 16a,17a-epoxy-20-keto-pregnane (61) (Scheme 8.22) [24]. 

Scheme 28. Employment of the Claisen-Eschenmoser rearrangement in the synthesis of + )-0-Methyljoubertiamine. Legend (7) is HCO EtlNaHIbenzene (2) CH2(CH2S-Ts)2-KOAc (i) LiAlHJTHF (4) MejA7-C(0 r)jMe (5) A (6) MeZ/MejCO or MeOff/TljO (7) LiAlH (8) MnOj,- (9) Dibal-HIArMe (10) Me2NH ArH MgSO then NaBH. ...

FIGURE 18.6 The aromatic Qaisen rearrangement in the synthesis of natural products. 

Several modifications of Claisen rearrangement were developed to increase the versatilities of this rearrangement in the synthesis of different classes of organic compounds. For instance, thermal rearrangement of allylic P-keto esters 112 to 112a are known as the CarroU-CIaisen rearrangements [77]. 

Mamedov VA, Kalinin AA, Gubaidullin AT, Gorbunova EA, Litvinov lA (2006) Quinoxaline-benzimidazole rearrangement in the synthesis of benzimidazole-based podands. Russ J Org Chem 42(10) 1532-1543. doi 10.1134/S1070428006100241... 

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