Rhodium-Catalyzed Intra- and Intermolecular [5 + 2] Cycloaddition of 3-Acyloxy-1,4-enyne and Alkyne with Concomitant 1,2-Acyloxy Migration

Shu, Xing‐Zhong; Li, Xiaoxun; Shu, Dongxu; Huang, Shih-Chien; Schienebeck, Casi M.; Zhou, Xin; Robichaux, Patrick J.; Tang, Weiping

doi:10.1021/ja2109097

Cited by 104 publications

(53 citation statements)

References 110 publications

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“…This is consistent with the effect of ester observed experimentally in Scheme 9. For the intramolecular cycloaddition, we were able to isolate a cyclopropane byproduct derived from cyclopropanation of cyclooctadiene, which supported the involvement of Rh(I) carbenes [34]. Computational studies predicted that when the Cl-ligand was placed on the trans-position, the Rh-carbon bond had more carbene character as shown in 46 .…”

Section: Resultsmentioning

confidence: 85%

“…Indeed, no seven-membered ring product was obtained after screening various metal catalysts [34]. The preference of the propargylic ester to undergo a 1,2 vs. 1,3 acyloxy migration is dependent on the nature of the substrate as well as the nature of the catalyst [32].…”

Section: Resultsmentioning

confidence: 99%

“…When we treated the mixture of ACE 28a and alkyne 29a with cationic catalyst ([Rh(COD) 2 ]BF 4 ) in the absence or presence of (CF 3 CH 2 O) 3 P ligand, no desired cycloaddition product 30a was observed [34]. Two molecules of ACE might coordinate to the cationic rhodium as bidentate ligands to form complex 31 and this would prevent the coordination of the two-carbon component alkyne.…”

Section: Resultsmentioning

confidence: 99%

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3-Acyloxy-1,4-enyne: A new five-carbon synthon for rhodium-catalyzed [5 + 2] cycloadditions

Schienebeck

Shu

et al. 2014

Pure and Applied Chemistry

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Seven-membered rings are ubiquitous in natural products and pharmaceutical agents and their syntheses continue to stimulate the development of novel synthetic methods. The (5+2) cycloaddition is one of the most efficient ways to access seven-membered rings since the 2-carbon components (alkenes, alkynes, or allenes) are readily available. Prior to our study, however, there was only one type of transition metal-catalyzed (5+2) cycloaddition: the reaction between vinylcyclopropanes and alkenes, alkynes, or allenes. We recently developed a new type of transition metal-catalyzed (5+2) cycloaddition, where the 5-carbon building block is 3-acyloxy-1,4-enyne (ACE). Our recent progress on Rh-catalyzed intra- and intermolecular (5+2) cycloadditions of ACEs and alkynes is summarized in this article. Using chiral propargylic esters, bicyclic products were prepared in high optical purity by the intramolecular (5+2) cycloadditions. Monocyclic seven-membered rings were synthesized by intermolecular (5+2) cycloaddition of ACEs and alkynes. Kinetic studies indicated that the rate of this intermolecular cycloaddition was significantly accelerated when the acetate was replaced by dimethylaminobenzoate. DFT calculations suggested that novel metallacycles were generated by a Rh-promoted oxidative cycloaddition of 1,4-enynes accompanied by a 1,2-acyloxy migration of propargylic esters.

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Section: Resultsmentioning

confidence: 85%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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3-Acyloxy-1,4-enyne: A new five-carbon synthon for rhodium-catalyzed [5 + 2] cycloadditions

Schienebeck

Shu

et al. 2014

Pure and Applied Chemistry

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“…Compounds 5a, [36] 5b, [37] and 5e [38] are known. General Procedure for the Synthesis of Diols 6a, 6c-6f: To a solution of substrate 5a, or 5c-5f (1.00 mmol) in THF (12 mL), AcOH (0.17 mL, 3.00 mmol) and tetra-n-butylammonium fluoride (TBAF; 0.95 g, 3.00 mmol) were added.…”

Section: Methodsmentioning

confidence: 99%

Synthesis of Alkynyl‐Glycinols by Lewis Acid Catalyzed Propargylic Substitution of Bis‐Imidates

2015

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Racemic and enantioenriched alkynyl‐glycinols can be synthesized by Lewis acid catalyzed cyclization reaction of bis‐trichloracetimidates derived from alkynyl‐glycols. The cyclization proceeds selectively to give 4‐alkynyl‐oxazolines as the propargylic substitution products. Enantioenriched bis‐imidates that contain an alkyl or trimethylsilyl substituent at the acetylene gave oxazolines with complete inversion of configuration. In turn, considerable racemization was observed in the cyclization of bis‐imidates that contain a phenyl substituent. The racemization for these substrates can be suppressed by introduction of the electronegative substituent at the phenyl ring. Oxazolines prepared by bis‐imidate cyclization reaction can be readily transformed to protected alkynyl‐glycol derivatives.

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“…67 Inspired by previous work on using 3-acyloxy-1,4-enynes as 5-carbon synthons for the synthesis of cyclopentenones and resorcinol derivatives, a [5+2] cycloaddition of 3-acyloxy-1,4-enynes with alkynes was developed by Tang’s group. 66, 68 …”

Section: Cycloadditions Involving Rh-catalyzed 12-acyloxy Migratimentioning

confidence: 99%

Rhodium-catalyzed acyloxy migration of propargylic esters in cycloadditions, inspiration from the recent “gold rush”

et al. 2012

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Transition metal-catalyzed acyloxy migration of propargylic esters offers versatile entries to allene and vinyl carbene intermediates for various fascinating subsequent transformations. Most π-acidic metals (e.g. gold and platinum) are capable of facilitating these acyloxy migration events. However, very few of these processes involve redox chemistry, which are well-known for most other transition metals such as rhodium. The coupling of acyloxy migration of propargylic esters with oxidative addition, migratory insertion, and reductive elimination may lead to ample new opportunities for the design of new reactions. This tutorial review summarizes recent developments in Rh-catalyzed 1,3- and 1,2-acyloxy migration of propargylic esters in a number of cycloaddition reactions. Related Au- and Pt-catalyzed cycloadditions involving acyloxy migration are also discussed.

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Rhodium-Catalyzed Intra- and Intermolecular [5 + 2] Cycloaddition of 3-Acyloxy-1,4-enyne and Alkyne with Concomitant 1,2-Acyloxy Migration

Cited by 104 publications

References 110 publications

3-Acyloxy-1,4-enyne: A new five-carbon synthon for rhodium-catalyzed [5 + 2] cycloadditions

3-Acyloxy-1,4-enyne: A new five-carbon synthon for rhodium-catalyzed [5 + 2] cycloadditions

Synthesis of Alkynyl‐Glycinols by Lewis Acid Catalyzed Propargylic Substitution of Bis‐Imidates

Rhodium-catalyzed acyloxy migration of propargylic esters in cycloadditions, inspiration from the recent “gold rush”

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