Alkynes dichlorobis

A degassed suspension of lhe halo compound 14 and an alkyne (1.2 equiv) in Et3N (0.1-0.2 mol) was stirred in the presence of dichlorobis(triphenylphosphane)palladium(II) (0.02 equiv) and coppcr(I) iodide (0.04 equiv) at 20 C for 20 h. EtOAc was added and the mixture was washed with H20 and brine the organic phase was dried (MgSOi) and evaporated to yield the product. 

A cyclopropane containing a C-Ti bond was also afforded when 1-phenylsulfonylcyclopropyl-lithium was allowed to react with chlorotriisopropoxytitanium. Two cyclopropyllithium entities were attacked by titanium, which resulted in formation of diisopropoxybis(l-phenylsulfonyl-cyclopropyl)titanium (3) in 69% yield.An analogous reaction took place when cyclopropyllithium was reacted with dichlorobis( 7 -cyclopentadienyl)titanium(IV) bis( / -cylopen-tadienyl)biscyclopropyltitanium(IV) (4) was obtained in 95% yield. Titanocene 4 reacts with alkynes (see Section 5.2.1.1.17.3.). 

ALKYNES Diacetatobis(ttiphenylphosphine)palladium(H). Dichlorobis(triphenyl-phosphine)palladium(H). Diethyl lithiodichloromethylphosphonate. 1,3-DiUthio-propyne. Iodine. Potassium hydroxide. Tetrakis(triphenylphosphine)palladium(0). 

The process starts with attack on the alkyne by the carbonyl carbon (R = ArCH2). In either a concerted reaction or through an intermediate carbocation (6) the chlorovinyl ketone is formed. Tanabe and Mukaiyama" preferred dichlorobis(trifluoromethanesulphonato) titanium(IV) as Friedel-Crafts catalyst over AICI3, TiC and Sn(OTf)2. After hydrolysis 1,3-diketones were obtained. 

Gerber R, Freeh CM (2012) Alkyne hydrothiolation catalyzed by a dichlorobis (aminophosphine) complex of palladium selective formation of cis-conflgured vinyl thioethers. Chem Fur J 18(29) 8901-8905... 

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