<b>Photochemical Reactions of 1,2-Diketones</b>

Urry, W. H.; Trecker, D. J.

doi:10.1021/ja00860a034

Cited by 71 publications

(18 citation statements)

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“…It has been proposed that the triplet diradical of the keto group triggers inter and intramolecular hydrogen transfers (35,36). This result is in agreement with the detailed studies of the photoreduction of biacetyl, reported recently by Turro and Engel (37).…”

Section: Discussionsupporting

confidence: 90%

Photoaddition of α-diketones to olefins. Stereospecificity of the addition reaction

Chow¹,

Joseph²,

Quon³

et al. 1970

Can. J. Chem.

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Phenanthraquinone (PQ) photolytically adds to cis-and trans-alkenes to give a mixture of cis-and trans-1,4-dioxenes and two reduction products. The ratios of cis-to trans-1,4-dioxenes remain the same irrespective of the photoaddition to cis-o r trans-alkenes and are 1:l for 2-butenes, 6:4 for 3-hexenes, and 8:2 for cyclohexene. A triplet excited phenanthraquinone is proposed as the reactive species which initiates the addition leading to the intermediate diradical 10. Depending on the nature of addenda the diradical 10 may be stabilized by a charge transfer structure in different conformations leading to the observed stereochemistry of the adducts. The PQ fails to add to fumaronitrile photolytically or thermally and thermally adds to 2-butenes only inefficiently. Biacetyl undergoes photoreduction readily in the presence of a large excess of cyclohexene.

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Section: Discussionsupporting

confidence: 90%

Photoaddition of α-diketones to olefins. Stereospecificity of the addition reaction

Chow¹,

Joseph²,

Quon³

et al. 1970

Can. J. Chem.

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“…Additionally, the 1,2-diketone moiety is known to be an excitable chromophore that can undergo Yang cyclization as opposed to the Norrish type II fragmentation. 28–33 …”

Section: Introductionmentioning

confidence: 99%

Approach for Expanding Triterpenoid Complexity via Divergent Norrish-Yang Photocyclization

Ignatenko

Tochtrop

2013

J. Org. Chem.

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Triterpenoids comprise a very diverse family of polycyclic molecules that is well-known to possess a myriad of medicinal properties. Therefore, triterpenoids constitute an attractive target for medicinal chemistry and diversity-oriented synthesis. Photochemical transformations provide a promising tool for the rapid, green and inexpensive generation of skeletal diversity in the construction of natural product-like libraries. With this in mind, we have developed a diversity-oriented strategy, whereby the parent triterpenoids bryonolic acid and lanosterol are converted to the pseudo-symmetrical polyketones by sequential allylic oxidation and oxidative cleavage of the bridging double bond at the B/C-ring fusion. The resultant polyketones were hypothesized to undergo divergent Norrish-Yang cyclization to produce unique 6/4/8-fused triterpenoid analogs. The subtle differences between parent triterpenoids led to dramatically different spatial arrangements of reactive functionalities. This finding was rationalized through conformational analysis to explain unanticipated photoinduced pinacolization, as well as the regio- and stereochemical outcome of the desired Norrish-Yang cyclization.

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“…The Norrish–Yang photocyclization has emerged as a powerful reaction for the synthesis of complex natural products . α-Diketone-based Norrish–Yang photocyclizations are particularly attractive because they can be used for direct construction of a cyclobutanone motif . However, application of the Norrish–Yang photocyclization for diastereoselective construction of the cyclobutanone in 1 is challenging because of the high steric repulsion among the substituents and the difficulties of achieving orbital overlap …”

Section: Introductionmentioning

confidence: 99%

Total Synthesis of (+)-Cyclobutastellettolide B

et al. 2021

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A convenient enantioselective total synthesis of (+)-cyclobutastellettolide B via a strategy that involves a diastereoselective Johnson−Claisen rearrangement, a regioselective cyclopropoxytrimethylsilane ring-opening reaction, and a Norrish− Yang cyclization is described. The results of computational and experimental studies indicate that the regio-and stereoselectivity of the Norrish−Yang reaction are controlled by the C−H bond dissociation energy and restricted rotation of the C13−C14 bond.

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Photochemical Reactions of 1,2-Diketones

Cited by 71 publications

References 1 publication

Photoaddition of α-diketones to olefins. Stereospecificity of the addition reaction

Photoaddition of α-diketones to olefins. Stereospecificity of the addition reaction

Approach for Expanding Triterpenoid Complexity via Divergent Norrish-Yang Photocyclization

Total Synthesis of (+)-Cyclobutastellettolide B

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