Propargyl alcohol protonation

Me3NO 2H20 forming HRu3(CO)7(dppm) C2CMe(OH)Ph whose structure and fluxionality have been studied. The substitution reaction occurs without dehydration of the coordinated propargyl alcohol. Protonation of the complex leads to HRu3(CO)v C2C(=CH2)Ph (Fig. 31). Neither reorientation of the acetylide nor formation of parallel alkynes is observed in this reaction.I l... 

Analogously, the 1,3-dipolar cycloaddition reaction of 2-diazopropane with propargyl alcohol 62b, performed at 0 °C in dichloromethane, was completed in less then 10 h and led to a monoadduct 63b with the same regioselective addition mode of 59 to the triple bond. The HMBC spectrum showed correlations between the ethylenic proton and the carbons C3 and C5 and between the methyl protons and the carbons C3 and C4. 

Protons on the 8 carbon of a ruthenium allenylidene complex are acidic, and deprotonation at this position often occurs to give ene-yne derivatives. Reaction of I with cyclic propargyl alcohols of type 110, for example, did not yield the allenylidene complexes, but rather the ruthenium ene-yne products (111) were isolated [Eq. (97)] (78). Reaction of the cor-... 

Propargyl alcohols can react with triiron dodecacarbonyl in unexpected ways one example is the deoxygenation of HC2C(Me)(OH)Ph to give a binuclear derivative (Fig. 24). This reaction can be compared with the WGSR reaction. A similar structure was obtained through a complex reaction pathway involving protonation and loss of MeOH from Fe2(CO)6[/r-C(OR)](/i-CR =CR H) (R = Me, Ft), Fig. 25." ... 

Coordination-dehydration reactions of propargyl alcohols have been followed in detail on triosmium clusters an example is given in Fig. 26.1 Protonation of triosmium clusters substituted with parallel alkynes leads to propargyl cationic derivatives which, in turn, can isomerize to allenylidene complexes. Fig. 27.1 ... 

Aldehydes and ketones can also be used as electrophiles in reactions with the vinylidene anion [Tp M( = C = CH2)(CO)2] . Low-temperature reaction of [Tp M( = C = CH2)(CO)2] with RR C = 0 (R = Ph, Pr, R = H R = Ph, R = Me) followed by protonation yields Tp W = CCH2C(OH)RR (CO)2. When R = Ph and R = H, one equivalent of base leads to deprotonation and hydroxide elimination to form the conjugated vinyl carbyne complex Tp W (= CCH = CHPh)(CO)2 (as the E isomer) in 53% yield two equivalents of base produces a 1 1 mixture of the vinyl carbyne and the ethylidyne complex. With base, Tp W = CCH2C(OH)PhMe (CO)2 simply regenerates the starting ethylidyne complex and ketone,reminiscent of the tendency of propargylic alcohols to eliminate aldehyde or ketone under basic conditions. 

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