Propargylic vinylic compounds

C=CHCH2NAtN=CR has been reported. " Propargylic vinylic compounds give allenic aldehydes, ketones, esters, or amides ... 

The Claisen rearrangement of propargyl vinyl ethers directly delivers the allene no equilibrium is observed. This reaction was also successful with complex substrates in order to show this, of numerous examples [375, 513-536], the compounds 159 [537] and 161 [538] are depicted (Scheme 1.71). 

The use of propargyl vinyl ethers prompted Toste et al. to develop a stereoselective preparation of 2-hydroxy-3,6-dihydropyrans, suitable for the synthesis of spirocyclic compounds. The reaction was catalyzed by a small amount (1 mol%) of [0(AuPPh3)3]... 

Hydrostannation of (l-alkynyl)carbene chromium complexes involves addition to the M = C bond as well as to the C=C bond and is strongly influenced by the substituent at the alkynyl moiety. By the bulky trimethyl-silyl group of compound lg, a 1,1-addition to the carbene carbon atom is promoted with formation of a densely functionalized 1,3-heterobimetal lie propargyl reagent 93 containing both a stannyl and a silyl group. A 3,1-addition is observed with phenyl derivative la and also the vinyl compound lo, which leads to production of an allene 94 and 95, respectively (Scheme 31).111... 

Reaction between sulfur trioxide and RRe(CO)6 (R = Me, Ph, and p-CgHiMe) in CCI4 and at 0°C leads to the formation of the sulfonato complexes, RS(0)a0Re(C0)5 (95). In contrast, propargyl derivatives of CpFe(CO)2, CpMo(CO)3, and Mn(CO)g yield metal-vinyl compounds... 

The corresponding vinylic carbenoid 6 or metallated a,/S-ethylenic nitrile 7, formed as a unique isomer, reacts in a second step with a stronger electrophile to give the polysubstituted vinylic compounds (Scheme 7-6). This reaction is of synthetic value for obtaining, as required, the two geometrical isomers 8 and 9 starting from the same propargylic ether [8]. 

Bohlmann (207) reported the reaction of /I -dehydroquinolizidine with methyl vinyl ketone and with propargyl aldehyde forming a partially saturated derivative of julolidine 135 and julolidine (136), respectively. Compound 135 can be prepared also by mercuric acetate dehydrogenation of ketone 137, which is formed by condensation of 1-bromoethylquinolizi-dine with ethyl acetoacetate (Scheme 11). 

Palladium And/Or Copper-Mediated Cross-Coupling Reactions Between 1-Alkynes And Vinyl, Aryl, 1-Alkynyl, 1,2-Propadienyl, Propargyl And Allylic Halides Or Related Compounds. A Review, Rossi. R. Carpita, A. Beilina, F. Org. Prep. Proceed. Int., 1995, 27, 129... 

A general method for the synthesis of highly substituted styrenes as 6/4-91, vinyl-cyclohexadienes and related compounds was developed by Xi, Takahashi and coworkers [301] by reacting an intermediately formed five-membered zirconacycle 6/4-89 with propargyl derivatives 6/4-90 or allyl bishalides in the presence of CuCl (Scheme 6/4.21). 

From the electronic populations on the vinylic hydrogens, the acidity of vinylic C—H was estimated to be higher in cyclopropenone than in cyclopropene (0.684 e/ 0.776 e). This agrees with kinetic measurements of the H-D-exchange at n-propyl cyclopropenone23 which showed an acidity of the vinylic C—H even higher than that of the acetylenic C—H in the reference compound propargyl alcohol. 

The reaction of alkynyllithium compounds with alkoxycarbene tungsten complexes leads to anionic propargyl tungsten complexes (Figure 2.33 see also Figure 3.9). These intermediates are stable at low temperatures and react upon Lewis acid catalysis with aldehydes or A -sulfonyl imines to yield five-membered heterocycles [280]. Oxidative methoxycarbonylation [375] of the intermediate vinyl tungsten complex, followed by elimination of methanol leads to pyrroles or furanes (Figure 2.33 Entry 6, Table 2.22). 

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