Rh(i)-Catalyzed enantioselective and scalable [4 + 2] cycloaddition of 1,3-dienes with dialkyl acetylenedicarboxylates

Abstract

A highly enantioselective and scalable intermolecular [4 + 2] cycloaddition to construct substituted cyclohexa-1,4-dienes.

Chemodivergent, Regio‐ and Enantioselective Cycloaddition Reactions between 1,3‐Dienes and Alkynes

“…Variations on the propiolate ester include those derived from primary, secondary and benzyl alcohols ( 3 e – 3 g ), all giving excellent regio‐ and enantioselectivities. Acetylene dicarboxylate underwent the reaction giving a product, 3 h ( er =90 : 10), a compound that had been reported in the literature [17] . Acetylenic ketones also proved to be good substrates ( 3 j – 3 l ) giving excellent enantioselectivities, even when the C3‐alkyl substituent carried a TBS‐protected alcohol ( 3 k ).…”

“…[14][15][16] There is one notable exception in a metal catalyzed cycloaddition, that of a single dienophile, dimethyl acetylenedicarboxylate, which gives useful levels of enantioselectivity (Figure 1A). [17] In addition to the limited scope of the dienophile, this reaction uses 10 mol % of prohibitively expensive [18] catalyst, [(norbornadiene) 2 Rh] + [BF 4 ] À ( � 9 turnovers) and 20 mol % of AgSbF 6 . The best enantioselectivity to date for a related cobalt-catalyzed [4+2]-cycloaddition reaction, which was originally discovered by Hilt in 2001, [19] is an only 71 % ee, [20] providing a challenging opportunity to develop this venerable reaction using an earth-abundant metal.…”

Unterscheidung der enantiotopen Seiten von strukturell unvoreingenommenen Carbeniumionen unter Verwendung einer cyclohexadienbasierten, chiralen Hydridquelle

“…Ideal geeignete rhodiumkatalysierte formale [4+2]‐Cycloadditionen wurden jüngst veröffentlicht. Zuerst von Hayashi [22] vorgestellt und von Shibata weiterentwickelt, [23] publizierte Zheng [24] eine Reaktionsvorschrift mit insgesamt guter Ausbeute und ausgezeichneten Enantioselektivitäten für ausgewählte Beispiele [25] . Unter Einsatz eines kationischen Rhodiumkomplexes in Kombination mit dem chiralen Phosphoramiditliganden L* wurden die angestrebten Cyclohexadiene greifbar (Schema 3).…”

Synthesis of Cyclic Fragrances via Transformations of Alkenes, Alkynes and Enynes: Strategies and Recent Progress

“…The design and screening of ligands would make it possible to achieve regioselectivity or even enantioselectivity. Recently, Shi et al developed an enantioselective [4 + 2] cycloaddition, catalyzed by a Rh(I) complex with a chiral phosphoramidite ligand [ 57 ]. The reaction can be efficiently scaled up by using 26.2 g (E)-1,3-nonadiene and 10 g dimethyl acetylenedicarboxylate to yield the product at 99% ee in 92% yield.…”