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Rearrangement amide enolate

Basic systematic investigations of amide enolate rearrangements concerning reaction conditions and diastereoselectivity have been pubUshed by Tsunoda et al. [Pg.485]

C4-insertions by means of a sigmatropic rearrangement process have been described using either a thermal Cope reaction, anionic Claisen amide enolate and zwitterionic aza-Claisen rearrangements. [Pg.173]

Somfai enhanced the driving force of some amide enolate aza-Claisen rearrangements by choosing vinylaziridines as reactants [24]. The additional loss of ring strain offered the advantage of running most of the reactions at room temperature to synthesize unsaturated chiral azepinones. Various substitution... [Pg.170]

The third mechanism starts with addition of the AT-allylamine 103 to the cumulated acceptor system of an allene carbonester 108 (Acc=CHC02Me) to form an intermediate iV-allyl ammonium amide enolate 109 (allene carbonester Claisen rearrangement). The anion stabilizing group is exclusively placed... [Pg.174]

Generally, ester enolates of structure (202 R = M, R = Oalkyl) rearrange via a 3,3-shift, whereas the corresponding amide enolates (202 R = M, R = N(alkyl)2) and acid dianions (202 R = M, R = OM) prefer the 2,3-pathway (equation 20). Both pathways have been observed with ketone enolates (202 R = M, R = alkyl). With substrate (179), Koreeda and Luengo observed only traces of Wittig rearrangement product (205), except for the lithium enolate, where (205) accounted for up to 20% of the reaction mixture (equation 21). ° Thomas and Dubini, however, reported predominant formation of 2,3 Wittig products (207) and (209) under base treatment of ketones (206) and (208) (equation 22). ... [Pg.851]

Pyrrolidinyl amides undoubtedly form Z((9)-enolates, and the [2,3]-Wittig rearrangement of the -alkene (entry 5, [69] is highly selective. The Z-alkene was not tested, and propargylic amide enolates do not rearrange [70]. Entry 5 also shows the highest yield in the Table. As will be seen, amides of C2-symmetric amines can be excellent chiral auxiliaries in this process. [Pg.236]

Scheme 6.14. Possible transition structures for the [2,3]-Wittig rearrangement of the R-allylic ester enolates shown in Scheme 6.13. For amide enolates, see Scheme 6.22. Scheme 6.14. Possible transition structures for the [2,3]-Wittig rearrangement of the R-allylic ester enolates shown in Scheme 6.13. For amide enolates, see Scheme 6.22.
Tsunoda et al. [43] have used this asymmetric amide enolate Claisen rearrangement in the total synthesis of (-)-iridomyrmecin 22 (Scheme 5.1.30). Rearrangement of the Z-enolate of the amide 23 via a chair like transition state generated, with a very high diastereoselectivity, the asymmetric centers a and P to the carbonyl group of the natural product. [Pg.227]

Recently, Tsunoda et al. [44] reported a chiral synthesis of (-)-antimycm using an amide enolate Claisen rearrangement. The rearrangement of the aUyUc amide 24, prepared by addition of N-trimethylsilyl (R)-a-methylbenzylamine to acrolein followed by acylation, gave the (7S,8R)-configured pentenoic amide 25 as an inseparable mixture with its (7R,8S) diastereomer (78% combined yield). This amide, which constitutes the C-6 to C-9 fragment of antimycin Ajt, was used to complete the synthesis (Scheme 5.1.31). [Pg.227]

Amide Acetal and Amide Enolate Claisen Rearrangements 483... [Pg.483]


See other pages where Rearrangement amide enolate is mentioned: [Pg.149]    [Pg.166]    [Pg.166]    [Pg.167]    [Pg.916]    [Pg.916]    [Pg.485]    [Pg.149]    [Pg.166]    [Pg.166]    [Pg.167]    [Pg.916]    [Pg.916]    [Pg.485]    [Pg.174]    [Pg.175]    [Pg.178]    [Pg.1208]    [Pg.168]    [Pg.170]    [Pg.173]    [Pg.182]    [Pg.363]    [Pg.458]    [Pg.476]    [Pg.203]    [Pg.1004]    [Pg.115]    [Pg.176]    [Pg.216]    [Pg.436]    [Pg.226]    [Pg.226]    [Pg.227]    [Pg.229]    [Pg.230]    [Pg.294]    [Pg.486]    [Pg.488]    [Pg.488]    [Pg.490]    [Pg.491]   
See also in sourсe #XX -- [ Pg.166 ]




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Amide enolate

Amide enolate Claisen rearrangement

Amide enolates 2,3]-Wittig rearrangement

Amides enolates

Amides rearrangement

Enol amidation

Enolates rearrangements

Enols rearrangement

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