Acyl-Claisen rearrangement synthesis

H-Azepine, 2-allyloxytetrahydro-Claisen rearrangement, 7, 508 3H-Azepine, 2-amino-acylation, 7, 511 effect of acidification, 7, 510 nucleophilic displacement reactions, 7, 514 synthesis, 7, 533, 535 3H-Azepine, 2-amino-7-bromo-synthesis, 7, 529 3H-Azepine, 2-anilino-ring inversion, 7, 495-499 structure, 7, 533... 

The strategy for the synthesis of y-butyrolactones by Claisen rearrangement of acylated 1,4-diols has been already discussed (Schemes 6-11). A stereodi-... 

Tetrafluoroethene has been used as a 2-carbon difluoroacetic acid equivalent, methodology developed by Normanl and co-workers, in the synthesis of inhibitors of Cobra venom phospholipase A2.13 Conversion of the allyl alcohols into the 2,2-difluoropent-4-enoic acids 32 is performed in one pot. The crude acids 32 are then converted into the methyl esters 33. Although esters 33 can be obtained directly from the acyl fluorides 29, as originally described by Normant and co-workers,10 a two-step procedure facilitates the workup after the Claisen rearrangement. 

Synthesis of trifluoromethylated compounds 152 has been achieved via ester-enolate [2,3]-Wittig and [3,3]-lreland-Claisen rearrangements. Perfluorocyclo-butane phosphonium ylides, e.g. 153, have been used as a masked fluoride anion source in their reactions with alcohols and carboxylic acids which lead to alkyl-and acyl-fluorides. Ylides 153 are also reported to cleave Si-C and Si-O bonds, cause dimerisation of fluoro-olefins, and also react with acid chlorides or other activated aromatic compounds under halogen exchange. ... 

In their total synthesis of (-i-)-ophiobolin in 1989, Kishi et al. found that treatment of a cyclopentenyl ester under the typical Ireland conditions gave principally C-silylated ester [63]. Heating of a C-silyl ester (prepared by acylation using a C-silyl acyl chloride) at 230 °C resulted in a 1,3-Brook rearrangement followed by an Ireland-Claisen rearrangement to give the desired product as a 6 1 ratio of isomers at C2 of the pentenoic acid (Scheme 4.63). The major product could have arisen through either a chair transition state of the Z-sUyl ketene acetal or a boat transition state of the E-silyl ketene acetal. 

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). 

Reviews cover the topics alkynethiolates in synthesis " oxygen-exchange reactions of sulphoxides sulphonyldiazomethanes C—S bond cleavage acyl isothiocyanates radical reactions of sulphur compounds addition of sulphenyl halides to olefins " sulphenamidcs mercaptoethylation of amines sulphur as a chiral centre " stereochemistry of S and S " compounds " reductive cleavage of sulphides, synthetic uses of alkene- and alkyne-thiolates, and thio-Claisen rearrangements nucleophilic displacements at sulphur in disulphides aromatic... 

---