De novo synthesis of functionalized 1,3-enynes and extended conjugated molecular systems

Abstract

Pd-catalyzed coupling of 1,3-dienyldibromides with triarylbismuths was demonstrated for the synthesis of a diverse range of 1,3-enynes. This study provided easy access to a range of functionalized 1,3-enynes in high yields utilizing triarylbismuths in sub-stoichiometric amounts. A new and concise route was unveiled for the synthesis of extended p-conjugated molecular systems with the help of chemoselective couplings and in conjunction with Sonogashira, Heck and arylation reactions under combined catalysis.

A concise route to functionalized benzofurans directly from gem-dibromoalkenes and phenols

“…The formation of 1-bromoalkyne in the presence of base was realized on our earlier studies both in the case of 1,1dibromoalkene 2a and 1,3-dienyldibromide. 14 Further it was evidenced by the isolation of the addition adducts 1c (Table 1) and 3c (Scheme 2). The second step of oxidative cyclization under palladium-catalyzed conditions is well represented in the literature towards benzofuran formation.…”

“…2,14 Melting points reported are uncorrected. Chromatographic purication of the products were performed using 100-200 and 230-400 mesh silica-gel with ethyl acetate/hexane as eluent.…”

Organobismuth Reagents: Synthesis, Properties and Applications in Organic Synthesis

“…For example, the palladium-catalyzed cross-coupling of 9-(dibromomethylene)-9H-fluorene provided the corresponding 9-(diarylmethylene)-9Hfluorenes in excellent yield. 253 In the case of monosubstituted 1,1-dibromoalkenes, cross-coupling with triarylbismuthines leads to internal alkynes. 254 Two mechanisms have been proposed for this transformation (Scheme 43 B).…”

Pd-Catalyzed cross-coupling synthesis of 4-aryl-3-formylcoumarins

“…The reactions utilizing triarylbismuths 11 allow cross-couplings with threefold organic electrophiles to afford threefold cross-coupled products under palladium-catalyzed conditions. 12,13 Several such threefold cross-coupling reactions involving triarylbismuth reagents with a variety of organic electrophiles such as acid chlorides, 12 a aryl halides, 12 b , c vinylic halides, 12 d , e heteroaryl halides, 12 f , g allylic halides, 12 h benzylic halides, 12 i bromo-quinones, 12 j 4-trifloxycoumarins, 12 k 4-halocoumarins, 12 k , l halochromones, 12 m etc. and the domino couplings of gem -dihalides 13 were studied by our group.…”