Rearrangements Claisen-lreland

Related reactions Carroll rearrangement, Claisen-lreland rearrangement, Eschenmoser-Claisen rearrangement, Johnson-Claisen rearrangement ... 

In acyclic systems the Claisen-lreland rearrangement proceeds via a chairlike transition state (TS). However, iri cyclic systems conformational constraints can override the inherent preference for chairlike TS and the boatlike TS becomes dominant. One explanation for the preference of boatlike transition states in cyclic systems is the destabilizing steric interactions of the silyloxy substituent and the ring atoms in a chairlike TS. ... 

The first chemical synthesis of an optically active trichodiene, (-)-trichodiene involved a Claisen-lreland rearrangement as the key step to connect the vicinal quaternary centers. J.C. Gilbert and co-workers found that the rearrangement occurred with complete facial selectivity and excellent diastereoselectivity to afford an advanced intermediate that was directly converted to (-)-trichodiene. 

CARROLL Rearrangement of Allyl Acetoacetic Esters Thermal condensation of allyl alcohols with ethyl acetoacetate in the presence of a catalyst, with loss of C02 a one pot ester exchange-Claisen-lreland rearrangement with loss of C02 (see 1st edition). 

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. ... 

Reaction of crotylsilanes with aryl acetals Panek and Yang1 have extended the Noyori reaction of allylsiianes with acetals catalyzed by trimcthylsilyl triflate (10,439-440) to optically active (E)-crotylsilanes, such as ar-methoxy-/ -(dimcthylphcnyl-silyl)-(E)-hexenoatcs (1). These (K)-crotylsilanes are available by lreland-Claisen ester rearrangement (6,276-277) of optically active vinylsilancs (equation 1 and 11). 

Soldermann, N. Velker, J. Vallat, O. Stoekli-Evans, H. Neier, R. "Application of the Novel Tandem Process Diels-Alder Reaction/lreland-Claisen Rearrangement to the Synthesis of rac-Juvabione and /ac-EpiJuvabione" Helv. Chim. Acta 2000, 63, 2266-2276. 

---