Enantioselective Synthesis of Functionalized Diazaspirocycles from 4‐Benzylideneisoxazol‐5(4<i>H</i>)‐one Derivatives and Isocyanoacetate Esters

Martínez‐Pardo, Pablo; Laviós, Adrián; Sanz‐Marco, Amparo; Vila, Carlos; Pedro, José R.; Blay, Gonzalo

doi:10.1002/adsc.202000611

Cited by 25 publications

(18 citation statements)

References 40 publications

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“…Active methylene group flanked by isocyano and ester 324 has been employed as 1,3-dipole in squaramide assisted cyclization process with isoxazole-5-ones 260 containing exocyclic olefinic functionality. [132] Bifunctional squaramide R' catalyzed the annulation to afford chiral spirocycles including pyrroline and isoxazole-5-one rings 325 with an overall yield of 12% along with 19 : 1 dr and 85% ee for the major diastereomer. The yield increased markedly when a catalytic amount of Ag 2 O was added to the system (55% yield, 3 : 1 dr, 80% ee for major diastereomer and 98% ee for minor diastereomer).…”

Section: Synthesis Of Heterocycles Containing N and Omentioning

confidence: 99%

Squaramide Catalyzed Asymmetric Synthesis of Five‐ and Six‐Membered Rings

Biswas¹,

Ghosh

Shankhdhar

et al. 2021

Asian J Org Chem

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Chiral analogues of squaramides have been fruitful in organocatalyzed asymmetric reactions over last decade. Alongside other H-bonding catalysts like ureas, thioureas: squaramides have been proved to be efficient asymmetric catalysts for the formation of acyclic and cyclic chiral molecules. A wide range of cyclic molecules bearing multiple functionalities and stereocenters have been synthesized by using several bifunctional squaramides as catalysts. These catalysts perform as base utilizing basic N atom in their chiral extension and help in stereoinduction by forming H-bonds with suitable H-bond acceptors. The present review focuses on assembling recent progresses of asymmetric synthesis of five and six membered rings promoted by squaramides. A handful of articles have been published by several research groups documenting asymmetric construction of five-and six-membered rings as part of interesting and complex molecular architectures. Different methodologies like conventional and formal cycloadditions or cascade reactions have been engineered through the assistance of chiral squaramides to fabricate the carbo-and heterocycles. This review also includes dual and cooperative catalytic system in which squaramide is one of the catalysts.

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Section: Synthesis Of Heterocycles Containing N and Omentioning

confidence: 99%

Squaramide Catalyzed Asymmetric Synthesis of Five‐ and Six‐Membered Rings

Biswas¹,

Ghosh

Shankhdhar

et al. 2021

Asian J Org Chem

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“…In a further increase on the structural variety of spirocyclic compounds, diazaspirocycles bearing three contiguous stereocenters and high functionalization were prepared diastereoand enantioselectively by the group of Pedro and Blay in 2020. [58] The new compounds were obtained by the reaction of isocyanoacetate esters and 4-arylideneisoxazol-5-ones promoted by a bifunctional squaramide/Brønsted base organocatalyst 19 derived from quinine cooperative and silver oxide as Lewis acid (Scheme 46). The reaction was compatible with the presence of aromatic substituents of different electronic character in the C4 position of the isoxazole-5-one as well as in the exocyclic double bond.…”

Section: Conflict Of Interestmentioning

confidence: 99%

Asymmetric Organocatalytic Synthesis of aza‐Spirocyclic Compounds from Isothiocyanates and Isocyanides

et al. 2021

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The spirocyclic motif is present in natural products, chiral ligands, and compounds of pharmacological interest. Isothiocyanates as well as isocyanides bearing electron-withdrawing groups in the α-position can be deprotonated and react as formal dipoles on account of the presence of a nucleophilic carbanion and an electrophilic atom in the isothiocyanate or isocyanide functional groups. In the last years a number of procedures involving the formal [3 + 2] cycloaddition reaction of isothiocyanates or isocyanides with cyclic compounds bearing electrophilic exocyclic double bonds have been developed for the enantioselective synthesis of aza-spirocyclic compounds. Among them, organocatalysis has played a predominant role in the development of asymmetric versions for these reactions. The synthesis of spirooxindoles by using this methodology has received especial attention, although other spirocyclic scaffolds are available depending on the structure of the dipolarophiles and the formal isothiocyanate and isocyanide dipoles.

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“…Recently, our group developed an asymmetric [3+2] cycloaddition between 4‐ylidene‐isoxazolinones and isocyanoacetates esters catalyzed by a chiral squaramide C30 and silver oxide [64] . This cooperative system gave functionalized diazaspirocycles with high to excellent yields and high stereoselectivities.…”

Section: ‐Ylidene‐isoxazolin‐5‐onesmentioning

confidence: 99%

Asymmetric Addition and Cycloaddition Reactions with Ylidene‐Five‐Membered Heterocycles

et al. 2021

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Five‐membered heterocycles bearing an exocyclic double bond have been successfully used as substrates in asymmetric addition and cycloaddition reactions. Ylidene‐heterocycles are attractive substrates due to their high functionalization and the presence of an electrophilic conjugated exocyclic double bound that can participate in nucleophilic addition reactions as well as cycloaddition reactions, which may be triggered by the formation of aromatic intermediates or products in many cases. During the last decades, catalytic methodologies have been developed using ylidene‐heterocycles as substrates in order to synthesize useful optically active heterocyclic derivatives. 4‐Ylidene‐pyrazol‐5‐ones, isoxazolin‐5‐ones, 2,3‐dioxopyrrolidines, rhodanines, oxazolidindiones, Erlenmeyer‐Ploch azlactones and 5‐ylidene‐thiazolones have been successfully used as substrates in asymmetric reactions. This review collects the powerful research in asymmetric addition and cycloaddition reactions where ylidene‐five‐membered heterocycles have been used.

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Enantioselective Synthesis of Functionalized Diazaspirocycles from 4‐Benzylideneisoxazol‐5(4H)‐one Derivatives and Isocyanoacetate Esters

Cited by 25 publications

References 40 publications

Squaramide Catalyzed Asymmetric Synthesis of Five‐ and Six‐Membered Rings

Squaramide Catalyzed Asymmetric Synthesis of Five‐ and Six‐Membered Rings

Asymmetric Organocatalytic Synthesis of aza‐Spirocyclic Compounds from Isothiocyanates and Isocyanides

Asymmetric Addition and Cycloaddition Reactions with Ylidene‐Five‐Membered Heterocycles

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