Palladium Catalyzed Hydrostannylation and Hydrogermylation of Acetylenes

Abstract

Treatment of acetylenes with Ph3SnH or Ph3GeH in the presence of a catalytic amount of Pd(PPh3)4 provides the corresponding alkenyltriphenylstannanes or alkenyltriphenylgermanes in good yields.

Regioselective Formation of (E)‐β‐Vinylstannanes with a Topologically Controlled Molybdenum‐Based Alkyne Hydrostannation Catalyst

“…[3,4] However,despite substantial progress in the development of alkyne hydrostannation catalysts,precise control over the hydrometalation regioselectivity continues to be an important challenge.S everal catalysts have now been reported that reliably provide a-vinylstannane products by catalyst-controlled hydrometalation (Scheme 1, top). [4,[12][13][14][15][16] Indeed, the only systems known to provide reasonable regioselectivities for (E)-b-vinylstannanes are highly encumbered palladium/phosphine catalysts that operate through af ormal Pd 0 /Pd II cycle. [4,[12][13][14][15][16] Indeed, the only systems known to provide reasonable regioselectivities for (E)-b-vinylstannanes are highly encumbered palladium/phosphine catalysts that operate through af ormal Pd 0 /Pd II cycle.…”

Hydrogermylation of 5-Ethynyluracil Nucleosides: Formation of 5-(2-Germylvinyl)uracil and 5-(2-Germylacetyl)uracil Nucleosides

“…Hydrogermylation of 1 with Ph 3 GeH in the presence of B(C 6 F 5 ) 3 22 in CH 2 Cl 2 at ambient temperature produced 2a in lower than 10% yields (TLC, 1 H NMR) while prolonged heating (48 h, reflux) produced a complex reaction mixture. The Pd(PPh 3 ) 4 -catalyzed hydrogermylation 19 of 1 with Ph 3 GeH in THF afforded a mixture of the expected E -isomer of 2a and the corresponding 5-[1-(triphenylgermyl)ethenyl] regioisomer, produced by addition of germyl radical to α-carbon, 19 in 3:2 ratio and 73% overall yield (entry 5; Method C). The acyl product 4a was not isolated from the reaction catalyzed by Pd(PPh 3 ) 4 .…”

New synthetic routes to allylic germatranes

“…Palladium-catalyzed hydrogermylation of terminal acetylenes by triphenyl germane, giving E-triphenylgermyl alkenes [13], and of isoprene by tri(2-furyl)germane [14] proceeds in both cases in good yield with marked stereochemical selectivity. We reasoned that allylic germatranes might also be prepared by the germatrane hydrogermylation of the corresponding dienes, Scheme 2.…”