Beyond olefins: new metathesis directions for synthesis

Abstract

This tutorial review provides an introduction to metathesis reactions between carbonyls and olefins or alkynes and their application in natural product synthesis.

AuCl3‐Catalyzed Ring‐Closing Carbonyl–Olefin Metathesis

“…Furthermore, ap oint to note is that stronge lectronwithdrawing groups, such as CF 3 and NO 2 ,w ere not compatible under the standard conditions, which is probably due to the isomerizationo ft he double bond in the substrates, promoted by the stronge lectron-withdrawingg roups.E ncouraged by the above results, we extended this protocol to seven-membered and five-membered benzocarbocycles (9a-i and 10 a-i). As expected, the corresponding benzo [7]annulene derivatives were obtained in good to excellent yield from the annulations of substituted benzaldehydes. Notably,a sf ar as indene derivatives were concerned, BiCl 3 was am ore suitable choice of catalyst than the AuCl 3 catalyst.…”

“…Substrate scopef or AuCl 3 -catalyzed aldehyde-olefin ring-closing metathesis. As expected, the corresponding benzo [7]annulene derivatives were obtained in good to excellent yield from the annulations of substituted benzaldehydes. [ b] Reaction time was 3min-3 h. [c] Reactiont ime increasedt o1 8-20 h. [d] 10 mol% BiCl 3 as catalyst, reaction time increased to 12-20h.[ e] Whenu sing 10 mol% of AuCl 3 and FeCl 3 as the catalyst,o nly 20 and 0% yieldsw ere obtained, respectively.…”

“…[7] In pioneering studies in 2012, Lambert established an organocatalytic [3+ +2]/retro[ 3 + +2]-cycloaddition approacht ot he synthesis of g,d-unsaturated aldehydes through carbonylolefin metathesis reactions, but the requirement of highly strained cyclopropenes as olefin components and the tedious preparation of the startingm aterials impeded its application (Scheme 1a). [7] In pioneering studies in 2012, Lambert established an organocatalytic [3+ +2]/retro[ 3 + +2]-cycloaddition approacht ot he synthesis of g,d-unsaturated aldehydes through carbonylolefin metathesis reactions, but the requirement of highly strained cyclopropenes as olefin components and the tedious preparation of the startingm aterials impeded its application (Scheme 1a).…”

“…;3)regenerationofs tartingc arbonyl-olefinpairs.Recently,t he real breakthrough has begun to dawn because of strategies and catalysts, such as the so-called catalytic carbonyl-olefin metathesis reactions that have been demonstrated. [7] In pioneering studies in 2012, Lambert established an organocatalytic [3+ +2]/retro[ 3 + +2]-cycloaddition approacht ot he synthesis of g,d-unsaturated aldehydes through carbonylolefin metathesis reactions, but the requirement of highly strained cyclopropenes as olefin components and the tedious preparation of the startingm aterials impeded its application (Scheme 1a). [8] Lamberth as subsequently extended this strategy to the synthesis of 2H-chromenes.…”

Characterizing Lewis Pairs Using Titration Coupled with In Situ Infrared Spectroscopy

“…. The Fe(III)-catalyzed carbonyl-olefin metathesis process, developed by the Schindler lab, exemplifies a powerful method for the production of C=C bonds from functional groups utilized ubiquitously in the construction of complex molecules 13,14,15 . Since the original report, this process has inspired a plethora of synthetic developments beyond the utilization of Fe(III) 16,17,18,19,20,21,22,23,24,25 .…”