An Efficient Route to 2-Substituted<i>N</i>-(1-Amino-3-methylpyrrol)amides by Ring-Opening Cyclization of Benzylidene- and Alkylidenecyclopropylcarbaldehydes with Hydrazides

Tang, Xiang‐Ying; Shi, Min

doi:10.1021/jo900730t

Cited by 22 publications

(16 citation statements)

References 9 publications

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“…On the basis of this structural analysis, the two substituents on the cyclopentene ring were identified as adopting a trans arrangement. On the basis of previous studies, [4,5] a plausible mechanism for the formation of 2 is outlined in Scheme 4. According to this scheme, the Wittig reaction of MCP aldehyde 1 with cinnamyltriphenylphosphonium bromide (or dimethyl cinnamylphosphonate) affords MCP alkenyl intermediate A in the presence of a base, which undergoes a Cope rearrangement via a chair-like transition state (TS) to give the corresponding cyclopentene product 2a.…”

Section: Resultsmentioning

confidence: 99%

“…[3] Previously, we reported a synthetic route to 2,3-disubstituted pyrrolamides by ring-opening recyclization of benzylidene and alkylidenecyclopropanecarbaldehydes with hydrazides. [4] In addition, we also reported an efficient method to stereospecifically synthesize transsubstituted cyclopentene derivatives in moderate to good yields by using the Cope rearrangement of readily available MCP alkenyl ketone derivatives (Scheme 1). [5] On the basis of the previous work, we hypothesized that MCPs with an activated alkene moiety might also be suitable substrates for the ring-opening process upon heating.…”

Section: Introductionmentioning

confidence: 99%

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Ring‐Opening Reaction of Methylenecyclopropanes Derived from Methylenecyclopropyl Aldehydes through Cope Rearrangement

2010

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Tandem Wittig reaction/Cope rearrangement of methylenecyclopropyl aldehydes 1 with cinnamyltriphenylphosphonium bromide afforded a convenient method for the synthesis of cyclopentene derivatives 2 in moderate yields in a one‐pot manner. Dialkyl 2‐[(2‐methylenecyclopropyl)methylene]malonates 3 derived from methylenecyclopropyl aldehydes 1 could produce two kinds of cyclopentene derivatives, 4 and 5, in good total yields through a thermally induced Cope rearrangement upon heating at 100 °C. Plausible reaction mechanisms are discussed on the basis of previous reports and on control experiments.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ring‐Opening Reaction of Methylenecyclopropanes Derived from Methylenecyclopropyl Aldehydes through Cope Rearrangement

2010

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“…37). 37 Bearing an ortho-amino on their aryl rings, the MCPs 86 reacted with aldehydes quickly and led to the intermediate 87.…”

Section: Pyrroles From Mcpsmentioning

confidence: 99%

Heterocycles from methylenecyclopropanes

et al. 2015

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The discovery of a series of novel organic reactions has made methylenecyclopropanes (MCPs) some of the most popular building blocks in synthetic organic chemistry during the past two decades. Among reported works, the construction of heterocycles from MCPs has highlighted new synthetic methodologies that afford more opportunities for the quick synthesis of elaborately substituted products, and this should draw a great deal of attention. However, reviews in this area are insufficient, and the latest monograph on heterocycle synthesis from MCPs was published 12 years ago. This review aims to summarize the novel organic reactions of MCPs to produce heterocycles published in recent years, which have provided specific and powerful tools for organic synthesis.

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“…[4] To date,the reactivity of ACPs has been predominantly unlocked by transition-metal catalysis, [1d,p] Lewis acid catalysis, [1b,i,n] radical-induced reactions, [5] and thermally induced cyclizations. [6] However,t othe best of our knowledge,t he organocatalytic activation of ACPs has not been reported.Phosphine catalysis [7] has emerged as afertile land for new reaction discovery.I np articular, electron-deficient allenes 1 exhibit remarkable reactivity in phosphine-catalyzed annulation reactions through apivotal zwitterionic intermediate A (Scheme 1). [7d,e,g,j] [3+ +2], [8] [4+ +2], [9] and [4+ +1] [10] annulations from the Lu, Kwon, and Tong groups,respectively,represent seminal advances in this area and have inspired am yriad of annulations, [11] including asymmetric variants.…”

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confidence: 99%

Phosphine‐Catalyzed Activation of Alkylidenecyclopropanes: Rearrangement to Form Polysubstituted Furans and Dienones

Tang

2019

Angewandte Chemie

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We report ap hosphine-catalyzed ring opening of electron-deficient alkylidenecyclopropanes (ACPs) to generate allylic phosphonium zwitterions that resemble the well-studied phosphine-allene adducts but exhibit distinct properties.T he potent reactivity of these intermediates has been demonstrated in three types of substrate-controlled phosphine-catalyzed rearrangements of alkylidenecyclopropylketones,w hichc hemoselectively affordt ri-and tetrasubstituted furans,a nd trisubstituted dienones in good yields.Alkylidenecyclopropanes (ACPs) [1] are at ype of extremely versatile yet readily available [2] building blocks in organic synthesis.B yv irtue of significant ring strain, [3] ap lethora of ring-opening reactions of ACPs have been developed for the construction of various molecular architectures. [4] To date,the reactivity of ACPs has been predominantly unlocked by transition-metal catalysis, [1d,p] Lewis acid catalysis, [1b,i,n] radical-induced reactions, [5] and thermally induced cyclizations. [6] However,t othe best of our knowledge,t he organocatalytic activation of ACPs has not been reported.Phosphine catalysis [7] has emerged as afertile land for new reaction discovery.I np articular, electron-deficient allenes 1 exhibit remarkable reactivity in phosphine-catalyzed annulation reactions through apivotal zwitterionic intermediate A (Scheme 1). [7d,e,g,j] [3+ +2], [8] [4+ +2], [9] and [4+ +1] [10] annulations from the Lu, Kwon, and Tong groups,respectively,represent seminal advances in this area and have inspired am yriad of annulations, [11] including asymmetric variants. [12] In an effort to expand the field of phosphine catalysis,w es urmised that electron-deficient alkylidenecyclopropanes (ACPs) 2 might be av iable substrate for nucleophilic phosphine catalysis, leading to an intriguing homologue intermediate B with unexplored reactivity and potential for new reaction discovery (Scheme 1). In continuation of our research in Lewis base catalysis, [13] we report herein the phosphine-catalyzed ringopening of electron-deficient ACPs in three types of substrate-controlled rearrangements of alkylidenecyclopropylketones,w hich chemoselectively afford tri-and tetrasubstituted furans,and trisubstituted dienones in good yields.Inspired by the elegant palladium-catalyzed rearrangement reactions of alkylidenecyclopropylketones reported by Ma and co-workers, [14] we initially examined the ring-opening reactivity of alkylidenecyclopropylketone 2-1 a under aset of phosphine-catalyzed conditions (Table 1). Gratifyingly,w ith acatalytic amount of PPh 3 (20 mol %) in DMSO at 120 8 8C, 2-1a underwent af acile rearrangement to afford trisubstituted furan 3a in 78 %yield (Entry 1). [15] Arange of alkyl and aryl phosphines were examined (Entries 2-8), in which P(4-MeOC 6 H 4 ) 3 outperformed all others tested, providing 3a in 81 %yield. Anucleophilic amine DABCO also promoted the ring opening of 2-1 a but generated 3-alkylidene-2,3-dihydrofuran 3a' ' [14b] in 54 %yield (Entry 9). Among several common solvents tested (Entrie...

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An Efficient Route to 2-SubstitutedN-(1-Amino-3-methylpyrrol)amides by Ring-Opening Cyclization of Benzylidene- and Alkylidenecyclopropylcarbaldehydes with Hydrazides

Cited by 22 publications

References 9 publications

Ring‐Opening Reaction of Methylenecyclopropanes Derived from Methylenecyclopropyl Aldehydes through Cope Rearrangement

Ring‐Opening Reaction of Methylenecyclopropanes Derived from Methylenecyclopropyl Aldehydes through Cope Rearrangement

Heterocycles from methylenecyclopropanes

Phosphine‐Catalyzed Activation of Alkylidenecyclopropanes: Rearrangement to Form Polysubstituted Furans and Dienones

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