Claisen rearrangement of allylic α-isocyano-esters—regioselective allylation of α-isocyanoesters at the α-carbon

Isocyanoacetate Derivatives: Synthesis, Reactivity, and Application

“…[17][18][19] Potassium salts 5 were used for synthesis of other different esters via alkylation. For example, esters 20-23 20,21 or solid-phase-bound isocyanocarboxylic acids 25-28 22 can be obtained by this method. Another approach is based on the deprotonation of benzyl isocyanides 13 with BuLi with subsequent carboxylation with CO 2 to afford a lithium salt 29.…”

“…However, the rearrangement did not lead to stereoselective allylation; the corresponding products 152 were isolated as diastereomeric mixtures (1:1-1:2). 21 In 1973, Scho ¨llkopf et al described the ring-opening of an oxirane with lithiated 2-isocyanopropionate. In this reaction, the oxirane can be regarded as an alkylating agent.…”

Claisen Rearrangement over the Past Nine Decades

“…The Ireland−Claisen rearrangement of allyl α-isocyanocarboxylates regioselectively afforded a C−C bond between the C-α of the α-isocyanoester and the C-3 of the allylic fragment, resulting in the α-allylation of isocyanoesters (Scheme ) 201 …”

“…The Ireland-Claisen rearrangement of allyl R-isocyanocarboxylates regioselectively afforded a C-C bond between the C-R of the R-isocyanoester and the C-3 of the allylic fragment, resulting in the R-allylation of isocyanoesters (Scheme 201). 224 The Johnson rearrangement was also reported as a method for the preparation of a range of functionalized carboxylic acid derivatives. Thus, the syntheses of 2-substituted acrylates and R-methylene-γbutyrolactones were described starting from methyl 3-(phenylseleno)orthopropionate via ortho ester-Claisen rearrangement followed by oxidative elimination of PhSeOH (Scheme 202).…”

Application of the Ester Enolate Claisen Rearrangement in the Synthesis of Amino Acids Containing Quaternary Carbon Centers

“…But the stereoselective generation of amino acids with chiral β-carbon centers is not a trivial issue and is therefore not yet well developed. Besides Michael- and cycloadditions, the sigmatropic rearrangement processes are suitable for this purpose . The major procedures applied to amino acid syntheses are the rearrangement of amino acid allylic esters via oxazole-intermediates, developed by Steglich, and the Ireland−Claisen rearrangement, , investigated by Bartlett …”