Asymmetric [4 + 3] Cycloadditions between Benzofuranyldiazoacetates and Dienes:  Formal Synthesis of (+)-Frondosin B

Olson, Jeremy P.; Davies, Huw M. L.

doi:10.1021/ol702844g

Cited by 81 publications

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References 27 publications

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“…Davies and co-worker [91–92] investigated the formal synthesis of the sequiterpene-hydroquinone derivative frondosin B ( 99 , see Scheme 12) [93] via an enantioselective cyclopropanation of trans -piperylene and subsequent divinylcyclopropane rearrangement, to further demonstrate the versatility of their formal [4 + 3] cycloaddition [82]. Starting from 4-methoxyphenol ( 90 ) Friedel–Crafts acylation and cyclization provided bicycle 91 .…”

Section: Reviewmentioning

confidence: 99%

Recent applications of the divinylcyclopropane–cycloheptadiene rearrangement in organic synthesis

Krüger¹,

Gaich²

2014

Beilstein J. Org. Chem.

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Section: Reviewmentioning

confidence: 99%

Recent applications of the divinylcyclopropane–cycloheptadiene rearrangement in organic synthesis

Krüger¹,

Gaich²

2014

Beilstein J. Org. Chem.

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“…[1] Among the different methods reported so far, the transition metal catalyzed [5+2] and [4+3] cycloadditions can certainly be considered as the most synthetically valuable. [2,3] They indeed allow a general, convergent, and efficient access to various seven-membered rings, with the possibility to rapidly and considerably increase the structural complexity when performed in an intramolecular manner.…”

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confidence: 99%

Gold‐Catalyzed Tandem Cycloisomerization/Cope Rearrangement: An Efficient Access to the Hydroazulenic Motif

Cao

Gagosz

2013

Angew Chem Int Ed

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“…This pathway involves a 1,2-acetoxy migration followed by a cyclopropanation/Cope rearrangement to produce the same product. Diazoesters undergo cyclopropanation/Cope rearrangement reactions in the presence of rhodium catalysts and Davies and coworkers have studied these reactions extensively 19,20…”

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confidence: 99%

Gold-catalyzed intermolecular [4C+3C] cycloaddition reactions

Gung

Bailey

Wonser

2010

Tetrahedron Letters

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In the presence of the N-heterocyclic carbene gold catalyst (NHC-AuIPr, 7), propargyl esters 1a-f and 13 undergo a [4C + 3C] cycloaddition reaction with cyclopentadiene and furan under mild conditions. The evidence suggests the formation of the seven-membered ring occurs by a direct cycloaddition process, rather than a stepwise cyclopropanation/Cope rearrangement sequence.The potent antiangiogenesis natural product family of cortistatins contain a center sevenmembered ring flanked by two six-membered rings. 1,2 Our initial attempt to construct the tetracyclic ring system using a transannular [4C+3C] cycloaddition strategy was met with mixed results. 3,4 In the same time, Mascarenas and co-workers reported an intramolecular [4C +3C] cycloaddition reaction, in which an allene functional group was selectively activated by Pt or Au catalyst. 5 This type of allene-diene intramolecular [4C+3C] cycloaddition reactions was further improved to occur under milder conditions. 6-8 Other reports using propargyl esters as reactants involved stepwise [4+3] cycloaddition reactions to prepare benzonorcaradienes and azepines. 9,10 More recently, Harmata reported the treatment of 5-silyloxydioxins with 5 mol % AuCl 3 /AgSbF 6 in the presence of cyclopentadiene or furan resulted in the formation of [4C+3C]-cycloadducts. 11 In this report, we disclose an intermolecular version of goldcatalyzed formal [4C+3C] cycloaddition reactions. This discovery expands the employment of propargyl esters as precursors in gold-catalyzed [4+3] cycloaddition reactions. 12 The likely mechanism for our recently reported gold-catalyzed transannular [4+3] cycloaddition could involve two possible pathways based on known examples in the literature. [13][14][15] The first pathway involves a gold-stabilized allyl cation and the second involves a gold carbene intermediate. As shown in Scheme 1, the first pathway (I to II through A and B) includes (1) a 3,3-rearrangement of the propargyl ester to give an allenyl ester (A), 16,17 (2) in situ activation by the same gold catalyst to generate an allyl cation B ,18 and (3) a [4+3] cycloaddition followed by a 1,2-acetoxy migration and deauration to produce the tetracyclic ring system II. The second mechanism through intermediates C and D is depicted on the right side in Scheme 1. This pathway involves a 1,2-acetoxy migration followed by a cyclopropanation/Cope rearrangement to produce the same product. Diazoesters undergo cyclopropanation/Cope rearrangement reactions in the presence of rhodium catalysts and Davies and coworkers have studied these reactions extensively. 19,20 Ohe and coworkers reported cyclopropanation of alkenes using propargylic carboxylates as vinylcarbene precursors and [RuCl 2 (CO) 3 ] 2 as the catalyst. 21 More recently, Au(I)-catalyzed Correspondence to: Benjamin W. Gung. Supplementary data Supplementary data associated with this article (experimental procedures, NMR spectra) can be found in the online version at Publisher's Disclaimer: This is a PDF file of an unedited manuscript that...

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Asymmetric [4 + 3] Cycloadditions between Benzofuranyldiazoacetates and Dienes: Formal Synthesis of (+)-Frondosin B

Cited by 81 publications

References 27 publications

Recent applications of the divinylcyclopropane–cycloheptadiene rearrangement in organic synthesis

Recent applications of the divinylcyclopropane–cycloheptadiene rearrangement in organic synthesis

Gold‐Catalyzed Tandem Cycloisomerization/Cope Rearrangement: An Efficient Access to the Hydroazulenic Motif

Gold-catalyzed intermolecular [4C+3C] cycloaddition reactions

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