Synthesis of Aminocyclobutanes through Ring Expansion of <i>N</i>-Vinyl-β-Lactams

Cheung, Lawrence L. W.; Yudin, Andrei K.

doi:10.1021/ol900118d

Cited by 42 publications

(13 citation statements)

References 31 publications

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“…[9] [b] Isolated yield. It should be noted that deprotonation of the eight-membered ring is faster than tautomerisation of the imine to the unreactive eight-membered enamide ring.…”

Section: Resultsmentioning

confidence: 99%

“…In the event, only the starting material was recovered, which suggests that the eight-membered en- [a] Conditions: N-vinyl b-lactam (20.0 mg), CuI (10 mol %), Cs 2 CO 3 (1.5 equiv), DMF (500 mL), microwave heating 30 min, 160 to 200 8C, see the Supporting Information. [9] [b] Isolated yield.…”

Section: Resultsmentioning

confidence: 99%

“…[8] We have been interested in the synthesis and transformations of b-lactam and cyclobutane ring systems and recently reported a synthetic method to make aminocyclobutanes from N-vinyl b-lactams in a highly stereoselective manner through a pericyclic cascade sequence. [9] Herein, we present an account of the synthetic utility of N-vinyl b-lactams, which includes the synthesis of eight-membered enamide rings through a sigmatropic ring expansion, the synthesis of aminocyclobutanes through a ring-strain transposition domino sequence. While dwelling on mechanistic underpinnings of this reaction, we also performed a computational study of the mechanism, which provides evidence for the intermediates postulated along the reaction pathway.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis of Highly Substituted Cyclobutane Fused‐Ring Systems from N‐Vinyl β‐Lactams through a One‐Pot Domino Process

Cheung

Yudin

2010

Chemistry A European J

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In this contribution, aminocyclobutanes, as well as eight-membered enamide rings, have been made from N-vinyl beta-lactams. The eight-membered products have been formed by a [3,3]-sigmatropic rearrangement, whereas the aminocyclobutanes have been derived from a domino [3,3]-rearrangement/6pi-electrocyclisation process. The aminocyclobutanes have been obtained in a highly diastereoselective fashion. The cyclobutane ring system tolerates fusion even if adjacent quaternary centres are present. Systems containing up to four fused rings are readily accessible. The reaction profile has been investigated by using Gaussian 03. This study suggests that two reaction pathways for aminocyclobutane formation are possible. In one pathway the [3,3]-sigmatropic rearrangement is the rate-limiting step and in the second pathway the electrocyclisation is rate limiting. Taken together, these reactions should facilitate the construction of fused heterocycles.

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“…[9] [b] Isolated yield. It should be noted that deprotonation of the eight-membered ring is faster than tautomerisation of the imine to the unreactive eight-membered enamide ring.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synthesis of Highly Substituted Cyclobutane Fused‐Ring Systems from N‐Vinyl β‐Lactams through a One‐Pot Domino Process

Cheung

Yudin

2010

Chemistry A European J

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“…The reaction has been carried out using tetrabutylammonium fluoride at room temperature, affording compound 97 in 62% yield. The synthesis of dihydropiperidin-2-ones 99 fused to a cyclobutene ring has been achieved from N-vinyl β-lactams 98 (Scheme 34) [38,39]. Reaction of Nvinyl β-lactams catalyzed by CuI (10 mol%), under microwave heating, gave the corresponding bicyclic products in moderate to very good yields (40-95%).…”

Section: Synthesis Of Six-membered Heterocyclesmentioning

confidence: 99%

Ring Expansions of β-Lactams and β-(thio)lactones

Alcaide

Almendros

Aragoncillo

2015

Topics in Heterocyclic Chemistry

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The skeleton of β-lactams and β-lactones is present in biologically active compounds. For example, the β-lactam ring is present in classical antibiotics such as penicillins and cephalosporins. On the other hand, there are several natural products containing a β-lactone moiety, with interesting inhibitory activity. In addition, both fragments are very useful synthetic intermediates for the preparation of cyclic and acyclic compounds. The ring strain present in both motifs is involved in this versatile reactivity. This chapter is devoted to the synthesis of five-to sevenmembered heterocycles by ring expansion of β-lactams and β-lactones. Different methodologies have been described, and the mechanism for the formation of the products has been discussed. In addition, the applicability of some of the processes has been demonstrated by the synthesis of fragments of natural or biologically relevant compounds. The contributions presented in this chapter have been selected mainly from the developments achieved in the last decade.

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“…The total synthesis of several natural products such as biotin [155], cribrostatin 4 [156], and himandrine [157] has also been carried out using 2-azetidinones as important building blocks. The syntheses of pyrrolizidines [158], fused prolines [159], oxazinones [160], amino glycals [161], aminocyclobutanes [162], bicyclic c-lactams [163], medium-sized heterocycles [164], and complex macrocycles [165] deserve to be mentioned as well.…”

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confidence: 99%

The Chemistry of 2‐Azetidinones (β‐Lactams)

Alcaide¹,

Almendros²,

Luna³

2011

Modern Heterocyclic Chemistry

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The large number of recent reports on b-lactam chemistry demonstrates the increasing interest in this important class of compounds. Monocyclic b-lactams frequently serve as precursors for the synthesis of classical bicyclic b-lactam antibiotics. The cyclic 2-azetidinone skeleton has been extensively used as a template on which to build the heterocyclic structure fused to the four-membered ring, using the chirality and functionalization of the b-lactam nucleus as a stereocontrolling element. The discovery of nonclassical b-lactam antibiotics, such as monobactams and nocardicins, coupled with ever-growing new applications such as enzyme inhibition has triggered a renewed interest in the building of new monocyclic b-lactam derivatives. Besides the utility of b-lactams as biologically active agents, they are used as intermediates in a-and b-amino acid synthesis, as well as building blocks for alkaloids, heterocycles, taxoids and other types of compounds of biological and medicinal interest. Physicochemical Data Computational ChemistryTheoretical studies show that b-lactams are weaker bases, in the gas phase, than acyclic amides [1]. The attenuation of basicity upon cyclization is stronger than that found for cyclic ketones of similar size due to the existence of a negative hyperconjugation effect that is present in b-lactams but not in cyclic ketones. Ab initio calculations indicate that both b-lactams and acyclic amides are oxygen bases, but the gap between the oxygen and nitrogen intrinsic basicities is much smaller in the former due to the aforementioned cyclization effects. This decrease of the oxygen Modern Heterocyclic Chemistry, First Edition. Edited

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Synthesis of Aminocyclobutanes through Ring Expansion of N-Vinyl-β-Lactams

Cited by 42 publications

References 31 publications

Synthesis of Highly Substituted Cyclobutane Fused‐Ring Systems from N‐Vinyl β‐Lactams through a One‐Pot Domino Process

Synthesis of Highly Substituted Cyclobutane Fused‐Ring Systems from N‐Vinyl β‐Lactams through a One‐Pot Domino Process

Ring Expansions of β-Lactams and β-(thio)lactones

The Chemistry of 2‐Azetidinones (β‐Lactams)

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