64788-21-2Relevant academic research and scientific papers
Diversification of ortho-Fused Cycloocta-2,5-dien-1-one Cores and Eight- to Six-Ring Conversion by σ Bond C?C Cleavage
Eccleshare, Lee,Lozada-Rodríguez, Leticia,Cooper, Phillippa,Burroughs, Laurence,Ritchie, John,Lewis, William,Woodward, Simon
, p. 12542 - 12547 (2016/08/24)
Sequential treatment of 2-C6H4Br(CHO) with LiC≡CR1(R1=SiMe3, tBu), nBuLi, CuBr?SMe2and HC≡CCHClR2[R2=Ph, 4-CF3Ph, 3-CNPh, 4-(MeO2C)Ph] at ?50 °C leads to formation of an intermediate carbanion (Z)-1,2-C6H4{CA(=O)C≡CBR1}{CH=CH(CH?)R2} (4). Low temperatures (?50 °C) favour attack at CBleading to kinetic formation of 6,8-bicycles containing non-classical C-carbanion enolates (5). Higher temperatures (?10 °C to ambient) and electron-deficient R2favour retro σ-bond C?C cleavage regenerating 4, which subsequently closes on CAproviding 6,6-bicyclic alkoxides (6). Computational modelling (CBS-QB3) indicated that both pathways are viable and of similar energies. Reaction of 6 with H+gave 1,2-dihydronaphthalen-1-ols, or under dehydrating conditions, 2-aryl-1-alkynylnaphthlenes. Enolates 5 react in situ with: H2O, D2O, I2, allylbromide, S2Me2, CO2and lead to the expected C-E derivatives (E=H, D, I, allyl, SMe, CO2H) in 49–64 % yield directly from intermediate 5. The parents (E=H; R1=SiMe3, tBu; R2=Ph) are versatile starting materials for NaBH4and Grignard C=O additions, desilylation (when R1=SiMe) and oxime formation. The latter allows formation of 6,9-bicyclics via Beckmann rearrangement. The 6,8-ring iodides are suitable Suzuki precursors for Pd-catalysed C?C coupling (81–87 %), whereas the carboxylic acids readily form amides under T3P conditions (71–95 %).
Development of a general copper-catalyzed vinylic Finkelstein reaction—application to the synthesis of the C1–C9 fragment of laingolide B
Nitelet, Antoine,Jouvin, Kévin,Evano, Gwilherm
, p. 5972 - 5987 (2016/09/16)
An efficient and broadly applicable procedure for the copper-catalyzed vinylic Finkelstein reaction is reported. Using a simple, readily available and cheap catalytic system, a broad range of alkenyl iodides and bromides can be smoothly converted to their lower homologues with high yields and full retention of the double bond geometry. Key features of this vinylic Finkelstein reaction are its broad applicability, enabling the conversion of readily available alkenyl iodides to their less available brominated and chlorinated counterparts, and the mild reaction conditions compatible with a range of highly functionalized substrates. The potential of this vinylic halogen exchange reaction in total synthesis and medicinal chemistry was demonstrated by its successful use for the synthesis of the C1–C9 fragment of laingolide B and for the late-stage modification of drug-like molecules. The extension of this halogen exchange to the acetylenic and allenic Finkelstein reactions is also reported.
One-Pot Cannizzaro Cascade Synthesis of ortho-Fused Cycloocta-2,5-dien-1-ones from 2-Bromo(hetero)aryl Aldehydes
Burroughs, Laurence,Eccleshare, Lee,Ritchie, John,Kulkarni, Omkar,Lygo, Barry,Woodward, Simon,Lewis, William
, p. 10648 - 10651 (2015/09/02)
An intramolecular Cannizzaro-type hydride transfer to an in situ prepared allene enables the synthesis of ortho-fused 4-substituted cycloocta-2,5-dien-1-ones with unprecedented technical ease for an eight-ring carboannulation. Various derivatives could be obtained from commercially available (hetero)aryl aldehydes, trimethylsilylacetylene, and simple propargyl chlorides in good yields. A cascade process that is triggered by an intramolecular Cannizzaro-type hydride transfer to an in situ prepared allene leads to the formation of 4-substituted cycloocta-2,5-dien-1-ones. Various derivatives could be obtained from commercially available (hetero)aryl aldehydes, trimethylsilylacetylene, and simple propargyl chlorides in good yields.
Novel, stereoselective and stereospecific synthesis of allenylphosphonates and related compounds via palladium-catalyzed propargylic substitution
Kalek, Marcin,Stawinski, Jacek
supporting information; experimental part, p. 1741 - 1755 (2011/09/15)
We have developed a novel method for the synthesis of allenylphosphonates and related compounds based on a palladium(0)-catalyzed reaction of propargylic derivatives with H-phosphonate, H-phosphonothioate, H-phosphonoselenoate, and H-phosphinate esters. The reaction is stereoselective and stereospecific, and provides a convenient entry to a vast array of allenylphosphonates and their analogues with diverse substitution patterns in the allenic moiety and at the phosphorus center. Some mechanistic aspects of this new reaction were also investigated. Copyright
Ene reaction of arynes with alkynes
Jayanth, Thiruvellore Thatai,Jeganmohan, Masilamani,Cheng, Mu-Jeng,Chu, San-Van,Cheng, Chien-Hong
, p. 2232 - 2233 (2007/10/03)
Arynes, generated in situ from ortho-silylaryl triflates, undergo ene reaction with alkynes possessing propargylic hydrogen in the presence of KF/18-crown-6 in THF at room temperature to give substituted phenylallenes. Various terminal and internal alkyne
