Carboxy .beta.-lactams by photochemical ring contraction

Stork, Gilbert; Szajewski, Richard P.

doi:10.1021/ja00825a015

Cited by 37 publications

(18 citation statements)

References 1 publication

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“…The combined filtrates were concentrated on an oil pump and the remainder recrystallized (EtOAc) to give the pure keto tautomer of 33 as a yellowish solid; yield: 307 mg (99%); mp 106°C [Lit. 67…”

Section: (5r)-5-isobutylpyrrolidine-24-dione (33)mentioning

confidence: 99%

Phosphorus Ylide Based Functionalizations of Tetronic and Tetramic Acids

Schobert¹,

Dietrich²,

Mullen³

et al. 2006

Synthesis

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The versatility of the ylide (triphenylphosphoranylidene)ketene (Ph 3 P=C=C=O, 3) in the construction of tetronic and tetramic acids from various carboxylic acid derivatives is demonstrated by new reactions and extensions of known ones. With a-hydroxy or a-amino esters, 3 affords tetronates or tetramates. A twostep synthesis of (-)-epi-blastmycinolactol shows that allyl a-hydroxy esters can be domino Wittig-Claisen reacted to give 3-allyltetronic acids. More extended Wittig-Claisen-Conia cascades can produce 3-alkylidenefuran-2,4-diones, the photooxygenation of which furnishes lactone endoperoxides with antiplasmodial potential. Tetronic acids can be acylated by 3 at C3 to give the corresponding acyl ylides. Their saponification yields the respective 3acetyl compounds, e.g. the fungal metabolite pesthetoxin. a-Hydroxy acids react with 3 to afford the corresponding 3-phosphoranylidenefuran-2,4-diones. The antibiotic (R)-reutericyclin was built up from benzyl D-leucinate and 3 in four steps by downstream acylation first at C3, then at N1 without racemization.

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Section: (5r)-5-isobutylpyrrolidine-24-dione (33)mentioning

confidence: 99%

Phosphorus Ylide Based Functionalizations of Tetronic and Tetramic Acids

Schobert¹,

Dietrich²,

Mullen³

et al. 2006

Synthesis

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“…In this context, the ring contractions of 2‐diazonaphthoquinones ( 1 ) into indene‐3‐carboxylic acid derivatives ( 2 )2−4 and related rearrangements of 3‐diazoquinolin‐4‐ones ( 3 ) into alkyl indole‐3‐carboxylates ( 4 )5−9 have been extensively studied. However, only a few examples of similar rearrangements in the α‐diazoamide series are known 10−12. Such rare examples include the photochemical ring contraction of 4‐diazopyrazolidine‐3,5‐diones into aza‐β‐lactams13,14 and sporadic instances of Wolff rearrangements in the acyclic α‐diazoamide series 15−17.…”

Section: Introductionmentioning

confidence: 99%

Ring Contractions of 4-Oxoquinolizine-3-diazonium Tetrafluoroborates, by an Aza Wolff Rearrangement, to Alkyl Indolizine-3-carboxylates

2001

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The 1-substituted 3-amino-4H-quinolizin-4-ones 13, available in two steps from 10 and methyl (Z)-2-benzyloxycarbonylamino-3-(dimethylamino)propenoate (11), were diazotized to give the stable diazonium tetrafluoroborates 7a and 7b. Heating of these diazonium salts in alcohols gave mixtures of 3-unsubstituted quinolizine derivatives 8a and 8b and the alkyl indolizine-3-carboxylates 9a−h. The ratio of the two types of products 8 and 9 was dependent on the type of alco-

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“…24 Second, no Wolff-type rearrangement products were formed in the reactions of the iodonium ylides which would be expected if ketocarbenes were involved as reactive intermediates. 25 However, heterocyclic rather than cyclopropane products have also been reported in carbenoid reactions of diazo compounds with a variety of multiple bonds including nitriles, acetylenes, carbodiimides, aldehydes and isothiocyanates 1a,26 and even with certain olefins. 27 In addition, the reactions of 2-diazonium phenoxides show remarkable similarities to those of the analogous phenyliodonium compounds.…”

Section: Introductionmentioning

confidence: 99%

Metal‐catalyzed carbenoid reactions with iodonium and sulfonium ylides

Müller

Fernández

Nury

et al. 1998

J. Phys. Org. Chem.

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Transition metal-catalyzed decomposition of phenyliodonium and diphenylsulfonium ylides was investigated with regard to application in asymmetric carbenoid reactions. Phenyliodonium ylides react in the presence of Rh(II) catalysts with the same selectivity in inter-and intramolecular cyclopropanations as the corresponding diazo compounds, and intramolecular CH insertions proceed with identical enantioselectivities. With diphenylsulfonium ethoxycarbonylmethylide the Cu(I)-catalyzed cyclopropanation of olefins affords trans/cis ratios and asymmetric inductions identical with those of diazo compounds, but with Rh(II) catalysts some small, although significant, selectivity variations occur, which are ascribed to coordination of diphenyl sulfide to one of the coordination sites of the catalyst. CARBENOID REACTIONS WITH PHENYLIODO-NIUM YLIDES Synthesis and thermal, and photochemical decomposition of phenyliodonium ylidesThe chemistry of phenyliodonium ylides has been pioneered by Neilands. 15 The ylides (4) are synthesized by heating activated methylene compounds (1) with iodosylbenzene (2) in chloroform. Other procedures use iodosylbenzene and acetic anhydride 16 or diacetoxyiodosylbenzene (3) in MeOH in the presence of KOH at À5 to 0°C. 17 This latter method of Schank 17 is the method of choice. It is, however, limited to ylides such as 4 carrying two electron-withdrawing substituents, such as carbonyl,

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Carboxy .beta.-lactams by photochemical ring contraction

Cited by 37 publications

References 1 publication

Phosphorus Ylide Based Functionalizations of Tetronic and Tetramic Acids

Phosphorus Ylide Based Functionalizations of Tetronic and Tetramic Acids

Ring Contractions of 4-Oxoquinolizine-3-diazonium Tetrafluoroborates, by an Aza Wolff Rearrangement, to Alkyl Indolizine-3-carboxylates

Metal‐catalyzed carbenoid reactions with iodonium and sulfonium ylides

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