33992-53-9Relevant articles and documents
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
supporting information, 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 %).
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
supporting information, 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.
Trifluoromethylation of propargylic halides and trifluoroacetates using (Ph3P)3Cu(CF3) reagent
Zhao, Tony S. N.,Szabó, Kálmán J.
supporting information; experimental part, p. 3966 - 3969 (2012/09/22)
A copper-mediated trifluoromethylation of propargylic halides and trifluoroacetates was performed with high allenyl or propargyl selectivity. The reaction proceeds smoothly with aliphatic and aromatic substituents bearing either electron-withdrawing or -s
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
Synthesis and reactivity of divinylselenium dichlorides and dibromides
Braverman, Samuel,Pechenick-Azizi, Tatiana,Gottlieb, Hugo E.,Sprecher, Milon
experimental part, p. 577 - 584 (2011/04/15)
Regio- and stereospecific electrophilic addition reactions of selenium tetrachloride and selenium tetrabromide to propargyl alcohols are reported. (Z,Z)-Bis(β-chlorovinyl)selenium dichlorides were isolated in high yields, and their reactivity was dependen
140. Acid-Catalyzed -Sigmatropic Rearrangements of N-Propargylanilines
Barmettler, Peter,Hansen, Hans-Juergen
, p. 1515 - 1573 (2007/10/02)
The acid-catalyzed rearrangement of N-(1',1'-dimethylprop-2'-ynyl)-, N-(1'-methylprop-2'-ynyl)-, and N-(1'-arylprop-2'-ynyl)-2,6-, 2,4,6-, and 2,3,5,6-, and 2,3,4,5,6-substituted anilines in mixtures of 1N aqueous H2SO4 and ROH such as EtOH, PrOH, BuOH etc., or in CDCl3 or CCl4 in the presence of 4 to 9 mol-equiv. trifluoroacetic acid (TFA) has been investigated (cf.Scheme 12-25 and Tables 6 and 7).The rearrangement of N-(3'-X-1',1'-dimethyl-prop-2'-ynyl)-2,6- and 2,4,6-trimethylanilines (X = Cl, Br, I) in CDCl3/TFA occurs already at 20 deg C with τ1/2 of ca. 1 to 5 h to yield the corresponding 6-(1'-X-3'-methylbuta-1',2'-dienyl)-2,6-dimethyl- or 2,4,6-trimethylcyclohexa-2,4-dien-1-iminium ions (cf.Scheme 13 and Footnotes 26 and 34).When the 4 position is not substituted, a consecutive -sigmatropic rearrangement takes place to yield 2,6-dimethyl-4-(3'-X-1'1'-dimethylprop-2'-ynyl)anilines (cf.Footnotes 26 and 34).A comparable behavior is exhibited by N-(3'chloro-1'-phenylprop-2'-ynyl)-2,6-dimethylaniline (45; cf.Table 7).The acid-catalyzed rearrangement of the anilines with a Cl substituent at C(3') in 1N aqueous H2SO4/ROH at 85-95 deg C, in addition, leads to the formation of 7-chlorotricyclo2,7>oct-3-en-8-ones as the result of an intramolecular Diels-Alder reaction of the primarily formed iminium ions followed by hydrolysis of the iminium function (or vice versa; cf.Schemes 13, 23, and 25 as well as Table 7).When there is no X substituent at C(1') of the iminium-ion intermediate, a -sigmatropic shift of the allenyl moity at C(6) occurs in competition to the -sigmatropic rearrangement to yield the corresponding 3-allenyl-substituted anilines (cf.Schemes 12, 14-18, and 20 as well as Tables 6 and 7).The rearrangement of (-)-(S)-N-(1'phenylprop-2'-ynyl)-2,6-dimethylaniline ((-)-38; cf.Table 7) in a mixture of 1N H2SO4/PrOH at 86 deg C leads to the formation of (-)-(R)-3-(3'-phenylpropa-1',2'-dienyl)-2,6-dimethylaniline ((-)-91), (+)-(E)- and (-)-(Z)-6-benzylidene-1,5-dimethyltricyclo2,7>oct-3-en-8-one ((+)-(E)- and (-)-(Z)-92, respectively), and (-)-(S)-2,6-dimethyl-4-(1'-phenylprop-2'-ynyl)aniline ((-)-93).Recovered starting material (10percent) showed a loss of 18percent of its original optical purity.On the other hand, (+)-(E)- and (-)-(Z)-92 showed the same optical purity as (-)-38, as expected for intramolecular concerted processes.The CD of (+)-(E)- and (-)-(Z)-92 clearly showed that their tricyclic skeletons possess enantiomorphic structures (cf.Fig. 1).Similar results were obtained from the acid-catalyzed rearrangement of (-)-(S)-N-(3'-chloro-1'-phenylprop-2'-ynyl)-2,6-dimethylaniline ((-)-45; cf.Table 7).The recovered starting material exhibited in this case a loss of 48percent of its original optical purity, showing that the Cl substituent favors the heterolytic cleavage of the N-C(1') bond in (-)-45.A still higher degree (78percent) of loss of optical activity of the starting aniline ...
