Showing papers by "Victor Snieckus published in 2008"
TL;DR: A Heck-like mechanism is proposed for this transformation of 5-aryl imidazo[1,5- a]pyrazines by palladium-catalyzed coupling of the corresponding 8-substituted derivatives with aryl halides.
63 citations
30 Jan 2008
44 citations
TL;DR: Carbanion-mediated general regioselective routes to acridones 4 and dibenzo[b,f]azepinones 20 are described and low energy conformations for compounds 18b and 23 indicate that the cyclization reactions are under kinetic control.
Abstract: Carbanion-mediated general regioselective routes to acridones 4 (Table 2) and dibenzo[b,f]azepinones 20 (Table 4) are described. Buchwald-Hartwig C-N cross coupling of o-halo benzamides 1 with anilines 2 or 16, followed by simple N-methylation, dependably provides N-methyl diarylamines 3 (Table 1) and 18 (Table 3). Upon treatment with LDA, 3 and 18 are converted into acridones 4 and dibenzo[b,f]azepinones 20, respectively, in good to excellent yields with regioselectivity which depends upon the presence or absence of directed metalation groups (DMGs). Brief investigations as follows are described: the synthesis of desmethyl acridone 15 (Scheme 4), an attempt to effect a double-directed remote metalation sequence which leads only to a monocyclization product 13 (Scheme 3), and an analogous but nonregioselective route to a xanthone 22 and dibenzo[b,f]oxepinone 24 (Scheme 5). DFT calculations reveal low energy conformations for compounds 18b and 23 which account for product formation and indicate that the cyclization reactions are under kinetic control.
42 citations
TL;DR: A new LDA-induced anionic N-C carbamoyl migration of 2-arylindoles is reported and its intramolecularity has been established by a crossover experiment.
40 citations
27 citations
TL;DR: A short synthesis of the alkaloid schumanniophytine (1) starting from simple building blocks and involving directed ortho metalation (DoM), Suzuki-Miyaura cross coupling, and a key ortho-silicon-induced O-carbamate remote anionic Fries rearrangement is described in this article.
15 citations
1 citations
1 citations
TL;DR: In this paper, a new LDA-induced anionic N−C carbamoyl migration of 2-arylindoles was reported, which has been applied to the synthesis of benzo[a]carbazoles 16 and indeno[1,2-b]indoles 18.
Abstract: A new LDA-induced anionic N−C carbamoyl migration of 2-arylindoles (7) is reported. Treatment of N-carbamoylindoles 10 and 13, readily available by direct and ipso-borodesilylative Suzuki−Miyaura cross-coupling routes from 8 and 12, respectively, provides a general route to functionalized 2-arylindoles 11 and 14, respectively (Tables 1 and 2). The reaction has been applied to the synthesis of benzo[a]carbazoles 16 and indeno[1,2-b]indoles 18, and its intramolecularity has been established by a crossover experiment (Scheme 4).
14 Mar 2008
TL;DR: In this article, the i-PP2B reagent was used in hydroboration of alkenes and alkynes and was stored at low temperatures (0°C) and used within several days of preparation.
Abstract: [501014-41-1] C16H31B (MW 234.23)
InChI = 1S/C16H31B/c1-11(2)9-15(13(5)6)17-16(14(7)8)10-12(3)4/h9-10,13-17H,1-8H3
InChIKey = XIXSBTKGTZXZFJ-UHFFFAOYSA-N
(reagent is used in hydroboration of alkenes and alkynes)
Physical Data: not available, reagent is generated and used in solution.
Solubility: soluble in THF.
Handling, Storage, and Precautions: Solutions of the i-PP2B reagent must be generated and handled under anhydrous conditions. It may be stored at low temperatures (0° C) and used within several days of preparation. Long-term storage of solutions of the reagent was not investigated. Protic solvents such as methanol and ethanol can be used to neutralize hydride activity of the reagent prior to disposal.