Synthesis and Reactivity of Oxazinoindolones via Regioselective 6‐exo‐dig Iodolactonization

Abstract

An efficient protocol for facile construction of 3,4-dihydro-10-iodo-3-iodomethylene-[1,4]oxazino[4,3-a]indol-1-ones has been developed by using a regio-and stereoselective iodolactonization reaction. Subsequent palladium cross-coupling reactions of 3,4-dihydro-10-iodo-3-iodomethylene-[1,4]-oxazino[4,3-a]indol-1-ones readily afforded functionalized oxazinoindolones.

Amidative Cyclization of Alkynyl Esters to Access Pyrazin-1(2H)-ones: Application to the Synthesis of Peramine and Dibromophakellin

“…5-Hydroxytryptamine (5-HT) with an indole core is an important synthon that plays a crucial role in serotonin receptors . In light of this, we embarked on extending our amidative exo -cyclization to N -propargyl indole-2-carboxylate S9 . Unfortunately, the reaction with benzylamine produced only 7% of the desired product 9a .…”

“…On the other hand, the THP-protected propargyl bromo derivative 14 was obtained in good overall yield from propargyl alcohol 11 in three steps following a reported procedure . Following the established protocol, the key intermediate 16 was obtained in 77% yield, as shown in Scheme . Preparation of intermediate 17 from 16 was expected via a direct tandem amidative exo -cyclization with NH 3 in MeOH (7.0 M) as an amine source using 0.4 equiv of TBD as in the case of the synthesis of 10a .…”

“…General Procedure E for the Synthesis of 16. 21 The compound 15a (1.0 equiv) in dry DMF was cooled to 0 °C, and to this reaction mass, NaH (1.2 equiv) was added portion-wise, followed by stirring for 30 min at the same temperature. Then, corresponding propargylic bromide 14 (1.2 equiv) in DMF was added dropwise at 0 °C over 10 min and the reaction mass was stirred for 12 h at room temperature.…”

Synthesis of Oxazino[4,3-a]indoles and biological applications

“…In a study dedicated to the synthesis and evaluation of tricyclic heterocycles as oxazolidinones as potential inhibitors of Mycobacterium tuberculosis UDP-galactopyranose mutase (Mt UGM), an enzyme involved in the biosynthesis of the galactan moiety of the cell wall, Thiery prepared various oxazinoindolones 45 from the iodolactonization of Npropargylindoles 44 [35,36] (Scheme 19). It was demonstrated that the iodolactonization was very effective with electron-rich and electron-poor substituents on indoles and tolerated alkyl and aromatic substituents on the alkyne triple bond (R 1 = Me, Ph).…”

Synthesis of New Highly Functionalized 1H-Indole-2-carbonitriles via Cross-Coupling Reactions

“…Stille coupling was performed using an organotin compound and a catalytic amount of dichlorobis(acetonitrile)palladium(II) in DMF at 40 • C (Scheme 8) [54,55]. Under these conditions, the coupling with compound 7a was successfully achieved, and two examples of coupling products (11b and 11c) were obtained in low to moderate yields (35-40%).…”