- A Versatile Route to Unstable Diazo Compounds via Oxadiazolines and their Use in Aryl–Alkyl Cross-Coupling Reactions
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Coupling of readily available boronic acids and diazo compounds has emerged recently as a powerful metal-free carbon–carbon bond forming method. However, the difficulty in forming the unstable diazo compound partner in a mild fashion has hitherto limited their general use and the scope of the transformation. Here, we report the application of oxadiazolines as precursors for the generation of an unstable family of diazo compounds using flow UV photolysis and their first use in divergent protodeboronative and oxidative C(sp2)?C(sp3) cross-coupling processes, with excellent functional-group tolerance.
- Greb, Andreas,Poh, Jian-Siang,Greed, Stephanie,Battilocchio, Claudio,Pasau, Patrick,Blakemore, David C.,Ley, Steven V.
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p. 16602 - 16605
(2017/12/13)
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- Preparation of Functionalized Diaryl- and Diheteroaryllanthanum Reagents by Fast Halogen–Lanthanum Exchange
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Aryl and heteroaryl halides (X=Br, I) undergo a fast and convenient halogen–lanthanum exchange with nBu2LaMe, which leads to functionalized diaryl- and diheteroaryllanthanum derivatives. Subsequent trapping reactions with selected electrophiles, such as ketones, aldehydes, or amides, proceeded smoothly at ?50 °C in THF, affording polyfunctionalized alcohols and carbonyl derivatives. Kinetic competition experiments revealed a similar reactivity trend as for Br/Mg exchange, but 106-times higher rates, making it comparable to Br/Li exchange.
- Benischke, Andreas D.,Anthore-Dalion, Lucile,Berionni, Guillaume,Knochel, Paul
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p. 16390 - 16394
(2017/11/28)
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- Synthesis of 1,2,4-trioxepanes and 1,2,4-trioxocanes via photooxygenation of homoallylic alcohols
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(Chemical Equation Presented) Homoallylic alcohols 4a-d, easily accessible in two steps from cyclopropyl methyl ketone, underwent a highly regioselective reaction with singlet oxygen to yield γ-hydroxyhydroperoxides 5a-d in 57-72% yield. Acid-catalyzed reaction of 5a-d with acetone, cyclopentanone, and cyclohexanone furnished 1,2,4-trioxepanes 8a-d, 9a-d, and 10a-d in good yields. Homoallylic alcohol 12 also underwent a highly regioselective photooxygenation to yield δ-hydroxyhydroperoxide 13 in 67% yield, which on reaction with acetone, cyclopentanone, and cyclohexanone, furnished 1,2,4-trioxocanes 16-18 in 41-55% yield.
- Singh, Chandan,Pandey, Shilpi,Saxena, Gunjan,Srivastava, Nisha,Sharma, Malvika
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p. 9057 - 9061
(2007/10/03)
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- REACTION OF 2,2-DISUBSTITUTED 1-(DIBROMOMETHYLENE)CYCLOPROPANES WITH METHYLLITHIUM
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In the reaction of 2,2-disubstituted 1-(dibromomethylene)cyclopropanes with methyllithium 4,4-disubstituted 1-buten-3-ynes and 2,2-disubstituted (1-bromoethylidene)cyclopropanes are formed in ratios which depend on the character of substitution in the cyclopropane ring.
- Kostikov, R. R.,Molchanov, A. P.,Nagi, Sh. M.
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p. 1291 - 1297
(2007/10/02)
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