A synergistic approach to polycyclics via a strategic utilization of Claisen rearrangement and olefin metathesis

Abstract

Olefin metathesis promoted by a well-defined metal carbene complex has evolved into an efficient method for the construction of a broad range of carbocyclic and heterocyclic rings of varying size. The synthetic potential of the olefin metathesis has been further increased by combining various other C-C bond forming processes either in tandem or in sequence. Herein, application of Claisen rearrangement and olefin metathesis to prepare various intricate and/or biologically important targets has been described.

Tandem RCM–Claisen Rearrangement–[2+2] Cycloaddition of O,O'-(But-2-en-1,4-diyl)-bridged Binaphthols

“…This requirement is often fulfilled with rearrangements proceeding via cyclic transition states and with sigmatropic rearrangements which represent stereospecific transformations. Typical examples are Cope and Claisen rearrangements and variations like Claisen-Ireland, Claisen-Johnsen, Meerwein-Eschenmoser-Claisen, thio- and aza-Claisen, and Carrol rearrangement [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. A special situation arises when atropisomeric biaryls are involved translating axial-chirality of the substrates into centro-chirality of the products provided the reaction proceeds at a temperature where no racemisation of the biaryl takes place.…”

Pd/TOMPP-catalysed telomerisation of 1,3-butadiene with lignin-type phenols and thermal Claisen rearrangement of linear telomers

“…After a single hydrogenation step, the resulting product mixtures provide suitable materials for the atom-efficient synthesis of alkyl phenol-based surfactants which are commercially produced for industrial detergent applications (Scheme 5). 17 Nevertheless, the two terminal olefins of the branched products, which are typically the main products of the Claisen reaction, also offer the opportunity for use as precursors in metathesis reactions such as ring closing metathesis (RCM) 18 and acyclic diene metathesis (ADMET). 19 In the case of RCM the octadienyl chain can be cyclized to give a cyclohexenyl group resulting in an aryl cyclohexyl motif which forms the basis for many different pharmaceutical ingredients.…”

Design and synthesis of polycyclic sulfones via Diels–Alder reaction and ring-rearrangement metathesis as key steps

“…Interestingly, we demonstrated trans -ring junction products are possible in the RRM protocol. It is clear that RRM has a unique place in olefin metathesis [ 38 – 45 ] and further interesting examples are expected in future.…”