Conversion of Beta-Lactams to Versatile Synthons via Molecular Rearrangement and Lactam Cleavage

Novel, simple, and convenient strategies to diversely functionalized spirocyclic b-lactams have been developed by using different metal-mediated carbonyl addition/cyclization reaction sequences. Spirocyclization precursors, 2-azetidinone-tethered homoallylic alcohols, bromohomoallylic alcohols, homopropargylic alcohols, (buta-1,3-dien-2-yl)methanols, and a-allenols have been obtained by regioselective addition of stabilized organometallic reagents to azetidine-2,3-diones in an aqueous environment. Ruthenium-, silver-, and palladium-catalyzed reactions of the above monocyclic unsaturated alcohol derivatives provided oxaspiro-b-lactams.

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Ring Expansion versus Cyclization in 4‐Oxoazetidine‐2‐ carbaldehydes Catalyzed by Molecular Iodine: Experimental and Theoretical Study in Concert

Alcaide

Almendros

Cabrero

et al. 2010

Adv Synth Catal

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Molecular iodine (10 mol%) efficiently catalyzes the ring expansion of 4-oxoazetidine-2-carbA C H T U N G T R E N N U N G aldehydes in the presence of tert-butyldimethylsilyl cyanide, or allylic and propargylic trimethylsilanes to afford protected 5-functionalized-3,4-dihydroxypyrrolidin-2-ones with good yield and high diastereoselectivity, through a C3 À C4 bond cleavage of the b-lactam nucleus. Interestingly, in contrast to the iodine-catalyzed reactions of 3-alkoxy-b-lactam aldehydes which lead to the corresponding g-lactam derivatives (rearrangement adducts), the reactions of 3-aryloxy-b-lactam aldehydes under similar conditions gave b-lactam-fused chromanes (cyclization adducts) as the sole products, through exclusive electrophilic aromatic substitution involving the C3 aromatic ring and the carbaldehyde. In order to support the mechanistic proposals, theoretical studies have been performed.

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Conversion of Beta-Lactams to Versatile Synthons via Molecular Rearrangement and Lactam Cleavage

Cited by 124 publications

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Additions of Allenyl/Propargyl Organometallic Reagents to 4-Oxoazetidine-2-carbaldehydes: Novel Palladium-Catalyzed Domino Reactions in Allenynes

Additions of Allenyl/Propargyl Organometallic Reagents to 4-Oxoazetidine-2-carbaldehydes: Novel Palladium-Catalyzed Domino Reactions in Allenynes

Diversity‐Oriented Preparation of Enantiopure Spirocyclic 2‐Azetidinones from α‐Oxo‐β‐lactams through Barbier‐Type Reactions followed by Metal‐Catalyzed Cyclizations

Ring Expansion versus Cyclization in 4‐Oxoazetidine‐2‐ carbaldehydes Catalyzed by Molecular Iodine: Experimental and Theoretical Study in Concert

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