The sequence of a stepwise AdE reaction and intramolecular Pauson-Khand cycloaddition as an entry into the synthesis of polycyclic compounds

Gybin, A. S.; Smit, V. A.; Caple, R.; Veretenov, A. L.; Шашков, А. С.; Воронцова, Л. Г.; Kurella, M. G.; Chertkov, V. S.; Karapetyan, A. A.

doi:10.1021/ja00040a012

Cited by 56 publications

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“… 451 , 452 Due to retigeranic acid’s intriguing structure, several research groups have pursued its synthesis and related sesterterpenoids. 453 − 455 Early examples of the total synthesis of retigeranic acid include reports by the groups of Corey, 456 Hudlicky, 457 − 460 and Paquette. 461 − 463 …”

Section: The Meta-photocycloaddition Reaction—a Powerful Methods For Amentioning

confidence: 99%

“…Pentacyclic (−)-retigeranic acid A ( 548 ), a structurally related natural product, was initially isolated from Himalayan lichen and is reported to have antibacterial activity. , It is a structurally unique member of the class of sesterterpene natural products and houses a triquinane subunit and eight stereocenters. , Due to retigeranic acid’s intriguing structure, several research groups have pursued its synthesis and related sesterterpenoids. − Early examples of the total synthesis of retigeranic acid include reports by the groups of Corey, Hudlicky, − and Paquette. − …”

Section: The Meta-photocycloaddition Reactiona Powerful Methods For ...mentioning

confidence: 99%

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Photochemical Approaches to Complex Chemotypes: Applications in Natural Product Synthesis

2016

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The use of photochemical transformations is a powerful strategy that allows for the formation of a high degree of molecular complexity from relatively simple building blocks in a single step. A central feature of all light-promoted transformations is the involvement of electronically excited states, generated upon absorption of photons. This produces transient reactive intermediates and significantly alters the reactivity of a chemical compound. The input of energy provided by light thus offers a means to produce strained and unique target compounds that cannot be assembled using thermal protocols. This review aims at highlighting photochemical transformations as a tool for rapidly accessing structurally and stereochemically diverse scaffolds. Synthetic designs based on photochemical transformations have the potential to afford complex polycyclic carbon skeletons with impressive efficiency, which are of high value in total synthesis.

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Section: The Meta-photocycloaddition Reaction—a Powerful Methods For Amentioning

confidence: 99%

Section: The Meta-photocycloaddition Reactiona Powerful Methods For ...mentioning

confidence: 99%

Photochemical Approaches to Complex Chemotypes: Applications in Natural Product Synthesis

2016

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“…Pure compounds 15 − 17a were obtained by flash chromatography (Scheme ). Other promoters, such as boiling toluene, wet silica gel, and NMO gave analogous results. Best yields were obtained for compound 15 in boiling toluene while TMANO was superior for compounds 16 and 17a .…”

Section: Resultsmentioning

confidence: 64%

Alkyne−Co₂(CO)₆ Complexes in the Synthesis of Fused Tricyclic β-Lactam and Azetidine Systems^,¹

1998

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A synthetic approach to racemic and enantiomerically pure, fused tricyclic 2-azetidinones and azetidines has been developed by using a Pauson-Khand (P-K) reaction on monocyclic enyne-beta-lactams as the key synthetic step. The access to cyclization precursors, monocyclic beta-lactams 1-7, was achieved by Staüdinger reaction of enyne imines 8 and 9 and D-glyceraldehyde imines 10 and (benzyloxy)- or phenoxyacetyl chlorides. Enyne imines 8 and 9 formed cis-2-azetidinones 1 and 2 having the required enyne moiety. cis-2-Azetidinones 11 were obtained as single diastereomers and transformed to enyne-2-azetidinones 3 and 5 by standard methodology. Alternatively, 4-formyl-2-azetidinones 14 were prepared by cyclization of p-anisyl glyoxal diimine and (benzyloxy)acetyl chloride and converted to racemic enyne-beta-lactams 4 and 6 by standard reactions. Enyne-2-azetidinones 1-7 were reacted with Co(2)(CO)(8) to quantitatively yield the corresponding alkyne-Co(2)(CO)(6) complexes. Reaction of such complexes with different promoters, especially heat and TMANO, formed tricyclic 2-azetidinones 15-19 with the ring system fused to the C3-C4 and C4-N1 lactam bonds. Yields were usually high, and the processes were highly diastereoselective. The exceptions were enyne-2-azetidinones 2 and 3a bearing N-propargyl moieties. These products decomposed to mixtures of unidentifiable products. Inhibition of the amide resonance was postulated as responsible for the failure of beta-lactams 2 and 3a to form tricyclic systems. In fact, the analogous enyne-azetidines 20a,b smoothly cyclized to form the corresponding tricyclic systems. This approach to tricyclic azetidines was extended to prepare different products. A new, unprecedented, N1-C2 bond breakage was also observed in the azetidine ring. The results described show that the P-K reaction is a suitable approach to tricyclic 2-azetidinones and azetidines. These are the first examples reported for a P-K reaction in with the enyne system is tethered to a strained heterocyclic four-membered ring.

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“…46 The cation was then trapped by an added nucleophile, methanol. This is most often by using the cation stabilization effect to form the substrate for the Pauson-Khand reaction.…”

Section: Synthesis Using Multiple Cobalt Reactionsmentioning

confidence: 99%

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2012

Organic Synthesis Using Transition Metals

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The sequence of a stepwise AdE reaction and intramolecular Pauson-Khand cycloaddition as an entry into the synthesis of polycyclic compounds

Cited by 56 publications

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Photochemical Approaches to Complex Chemotypes: Applications in Natural Product Synthesis

Photochemical Approaches to Complex Chemotypes: Applications in Natural Product Synthesis

Alkyne−Co₂(CO)₆ Complexes in the Synthesis of Fused Tricyclic β-Lactam and Azetidine Systems^,¹

Reactions of Alkyne Complexes

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The sequence of a stepwise AdE reaction and intramolecular Pauson-Khand cycloaddition as an entry into the synthesis of polycyclic compounds

Cited by 56 publications

References 0 publications

Photochemical Approaches to Complex Chemotypes: Applications in Natural Product Synthesis

Photochemical Approaches to Complex Chemotypes: Applications in Natural Product Synthesis

Alkyne−Co2(CO)6 Complexes in the Synthesis of Fused Tricyclic β-Lactam and Azetidine Systems,1

Reactions of Alkyne Complexes

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Alkyne−Co₂(CO)₆ Complexes in the Synthesis of Fused Tricyclic β-Lactam and Azetidine Systems^,¹