Organocatalytic decarboxylative aldol reaction of β-ketoacids with α-ketophosphonates en route to the enantioselective synthesis of tertiary α-hydroxyphosphonates

Vamisetti, Ganga B.; Chowdhury, Raghunath; Ghosh, Sunil K.

doi:10.1039/c7ob00796e

Cited by 30 publications

(10 citation statements)

References 67 publications

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“…In 2017 an organocatalytic decarboxylative aldol reaction of β-ketoacids with α-ketophosphonates allowed the enantioselective synthesis of tertiary α-hydroxyphosphonates was described by Chowdhury and coworkers for the first time (Figure 43) [83]. α-Hydroxyphosphonates have been shown to exhibit many kinds of useful biological activities, including in reports by one of us, and they are the object of much research [84][85][86].…”

Section: Aldol and Henry Reactionsmentioning

confidence: 99%

Non-Covalent Interactions in Enantioselective Organocatalysis: Theoretical and Mechanistic Studies of Reactions Mediated by Dual H-Bond Donors, Bifunctional Squaramides, Thioureas and Related Catalysts

2021

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Chiral bifunctional dual H-bond donor catalysts have become one of the pillars of organocatalysis. They include squaramide, thiosquaramide, thiourea, urea, and even selenourea-based catalysts combined with chiral amines, cinchona alkaloids, sulfides, phosphines and more. They can promote several types of reactions affording products in very high yields and excellent stereoselectivities in many cases: conjugate additions, cycloadditions, the aldol and Henry reactions, the Morita–Baylis–Hilman reaction, even cascade reactions, among others. The desire to understand mechanisms and the quest for the origins of stereoselectivity, in attempts to find guidelines for developing more efficient catalysts for new transformations, has promoted many mechanistic and theoretical studies. In this review, we survey the literature published in this area since 2015.

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Section: Aldol and Henry Reactionsmentioning

confidence: 99%

Non-Covalent Interactions in Enantioselective Organocatalysis: Theoretical and Mechanistic Studies of Reactions Mediated by Dual H-Bond Donors, Bifunctional Squaramides, Thioureas and Related Catalysts

2021

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“…In 2017, the Chowdhury group employed β-aryl-β-keto acids 185 as a surrogate for acetophenone enolate to realize the first example of asymmetric decarboxylative hydrophosphonylation. 102 The quinidine-based bifunctional urea catalyst 186 was the preferred catalyst for this reaction and afforded chiral tertiary α-hydroxyphosphonates 187 bearing a quaternary center in moderate to good yields and enantioselectivities (Scheme 55). NMR studies suggest that the reaction begins with the addition of the enolate of β-keto acid to the α-ketophosphonate forming the intermediate I, followed by decarboxylation to 187.…”

Section: Scheme 53 Asymmetric Cross-aldol Reaction Of Racemic α-Ketopmentioning

confidence: 99%

Recent Advances in the Catalytic Asymmetric Construction of Phosphorus-Substituted Quaternary Carbon Stereocenters

Chen

2017

Synthesis

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Phosphorus-substituted quaternary carbon stereocenters exist widely in drugs and biologically active compounds. Catalytic asymmetric synthesis of such quaternary carbon stereogenic centers is of significant importance, with four synthetic strategies being established. This review summarizes the recent progress in this field, including the advantages and limitations of each strategy, briefly discusses the reaction mechanisms and challenges, and outlines synthetic opportunities still open.1 Introduction2 Asymmetric Hydrophosphonylation3 Asymmetric Electrophilic Phosphination4 Asymmetric Functionalization of P-Substituted Methine Compounds5 Asymmetric Addition to α-Keto- or α-Ketiminophosphonates6 Conclusion

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“…More recently, Fu, Huang and co‐workers developed carbene‐catalysed formal [4+2] annulation of enals with β‐silyl enones to form enantiopure organosilanes (Scheme D) . As part of our recent interest on catalytic enantioselective synthesis of organic molecules bearing a silyl‐substituted asymmetric carbon and in general development of bifunctional thio(urea) catalysed reactions,, we envisaged that organocatalyzed conjugate addition of nitroalkanes to β‐silylmethylene malonates would be the most straightforward approach to rapid access of enantioenriched organosilanes (Scheme E).…”

Section: Introductionmentioning

confidence: 99%

Organocatalyzed Diastereo‐ and Enantioselective Conjugate Addition of Nitroalkanes to β‐Silylmethylene Malonates: Direct Access to Enantioenriched Organosilanes

2020

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Cinchona-alkaloid derived bifunctional thiourea catalyzed conjugate addition reaction of nitroalkanes to -silylmethylene malonates is reported for direct access of densely functionalized enantioenriched organosilanes in good yields (up to 86 %) with excellent stereoselectivities (up to 98:2 dr and 90 % ee). Using pseudoenantiomeric catalyst, both the enantiomers of the conjugate addition products were easily accessible. Preparative scale synthesis of two conjugate addition products [a] Dr. Scheme 1. Selected state-of-the-art strategies for the synthesis of chiral organosilanes under organocatalytic conditions and present work.nitromethane to aryl/alkylidene malonates took place with moderate yields and long reaction time (3-5 days) in presence of 10 mol-% catalyst and nitromethane as a solvent. In addition, bifunctional iminophosphorane catalysed Michael addition of nitroalkanes to enone diesters is also reported. [19] However, to the best of our knowledge, organocatalytic asymmetric conjugate addition reaction of nitroalkanes to -silylmethylene malonates has not been studied so far. In this paper, we disclose the first catalytic conjugate addition of nitroalkanes including nitromethane to -silylmethylene malonates for the diastereoand enantioselective synthesis of chiral organosilanes (Scheme 1 E). The important feature of these conjugate addition products is the presence of different functional groups which could be useful for downstream synthetic transformation. Results and DiscussionInitially, we started the optimization studies by screening readily available bifunctional hydrogen-bonding organocatalysts [20] I-XII (Figure 2) for the Michael addition reaction betweensilylmethylene malonate1a and nitromethane 2a in toluene as a solvent. To our delight, quinidine derived thiourea catalyst I Eur. 2964 and good enantioselectivities (80-90 % ee) ( Table 2). Thesilylmethylene malonate 1e with the bulky tert-butyldiphenylsilyl group also participated in the conjugate addition reaction in presence of 20 mol-% of catalyst VI at room temperature and

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Organocatalytic decarboxylative aldol reaction of β-ketoacids with α-ketophosphonates en route to the enantioselective synthesis of tertiary α-hydroxyphosphonates

Cited by 30 publications

References 67 publications

Non-Covalent Interactions in Enantioselective Organocatalysis: Theoretical and Mechanistic Studies of Reactions Mediated by Dual H-Bond Donors, Bifunctional Squaramides, Thioureas and Related Catalysts

Non-Covalent Interactions in Enantioselective Organocatalysis: Theoretical and Mechanistic Studies of Reactions Mediated by Dual H-Bond Donors, Bifunctional Squaramides, Thioureas and Related Catalysts

Recent Advances in the Catalytic Asymmetric Construction of Phosphorus-Substituted Quaternary Carbon Stereocenters

Organocatalyzed Diastereo‐ and Enantioselective Conjugate Addition of Nitroalkanes to β‐Silylmethylene Malonates: Direct Access to Enantioenriched Organosilanes

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