Construction of tetralin skeletons based on rhodium-catalysed site-selective ring opening of benzocyclobutenols

Abstract

Tetralins (tetrahydronaphthalenes) are synthesised from benzocyclobutenols based on the rhodium-catalysed site-selective ring opening followed by intermolecular/intramolecular conjugate addition of the resulting arylrhodium species to electron-deficient alkenes. The produced structures make a remarkable contrast with those available from the same compounds under thermal reaction conditions.

Rhodium(i)-catalyzed stereoselective [4+2] cycloaddition of oxetanols with alkynes through C(sp3)–C(sp3) bond cleavage

“…4 In 2012, Murakami and co-workers reported seminal work on rhodium-catalyzed tandem C–C single bond cleavage/formal cycloaddition of benzocyclobutanols with alkynes [eqn (1)]. 4 b Since then, vinyl ketones, 5 carbene precursors, 6 and allenes 7 have been proven to be suitable cycloaddition counterparts, demonstrating the broad applicability of this protocol [eqn (2)–(4)]. However, to the best of our knowledge, under rhodium catalyzed cycloaddition with unsaturated 2-π systems, ring opening of cyclobutanols exclusively occurred on the C(sp 2 )–C(sp 3 ) bond adjacent to the hydroxyl group, with subsequent addition of the ipso carbon [ i.e.…”

Synthesis of Multiply Substituted Polycyclic Aromatic Hydrocarbons by Iridium‐Catalyzed Annulation of Ring‐Fused Benzocyclobutenol with Alkyne through C−C Bond Cleavage

“…[7,8] Recently,Murakami et al and Wang et al reported the rhodium-catalyzed cyclization of BCB with alkynes or diazo esters,r espectively. [7,8] Recently,Murakami et al and Wang et al reported the rhodium-catalyzed cyclization of BCB with alkynes or diazo esters,r espectively.…”

“…[9] We are interested in ring-fused benzocyclobutenols (RBCB) as they can be easily obtained using ao ne-step synthesis from commercially available aryl bromides and cyclic ketones. [7,11,12] We recently reported the silver-o rm anganese-catalyzed distal CÀCbond cleavage of RBCB to generate medium-sized carbocyclic fluorides or azides (Scheme 1, path (a)). Theb enzocyclobutyl C À C bond can be cleaved in "distal" or "proximal" pathway.…”

“…Benzocyclobutenols (BCB) are frequently employed as privileged building blocks for the construction of complex cyclic molecules and natural products. [7,8] Recently,Murakami et al and Wang et al reported the rhodium-catalyzed cyclization of BCB with alkynes or diazo esters,r espectively. [7b,e] However,t he reactions required high temperature (100 8 8C), the utility of products was not fully demonstrated, and most importantly,the preparation of BCB usually requires tedious synthetic routes.…”

“…Theb enzocyclobutyl C À C bond can be cleaved in "distal" or "proximal" pathway. [7,11,12] We recently reported the silver-o rm anganese-catalyzed distal CÀCbond cleavage of RBCB to generate medium-sized carbocyclic fluorides or azides (Scheme 1, path (a)). [13] Inspired by these findings,itisconceivable that the cyclization of alkyne with RBCB by means of proximal C À Cc leavage might lead to polyaromatic compounds.H erein, we disclose the first iridium-catalyzed annulation of RBCB with alkynes to efficiently produce av ariety of multiply substituted PA Hs in good yields (Scheme 1, path (b)).…”