AUyl carbonates

Nucleophilic addition to the (syn,anti-l,3-dimethyl)aUyl Ugand of cation XIX yields the olefin complex XX, a diastereoisomer of complex XVIII, demonstrating that the configuration in the cation of the aUyl carbon that undergoes nucleophilic attack determines the configuration of that carbon in the product . 

In another method, phosgene is gradually passed into 1,2-propylene glycol (9). The chloroformate is washed, dried, and distilled at 266 Pa (2 mm Hg) and added slowly to a mixture of aUyl alcohol and pyridine below 15°C. The purified monomer 1,2-propylene glycol bis(aUyl carbonate) (C.. H O ) heated with lauroyl peroxide at 70°C gives a hard clear, polymer. 

COF coefficient of friction CR-39 diethylene glycol bis-aUyl carbonate... 

N. N. Barashkov, T. V. Sakhno, N. N. Alekseev, T. M. Murav eva, L. M. Bulgakova, and L. A. Gorbunov. Spectral and luminescence properties of copolymers of poly(methy methacrylate) and poly(aUyl carbonate) with fragments of anthracene and diphenyloxadiazole. Zh. Prikl. Spektws., 53 386-391, 1990. 

Palladium(0)-Catalyzed Introduction of a-Tocopherol (Vitamin E) and Ostradiol into the AUyl Carbonates of Methyl 10-Undecenoate and Methyl Oleate... 

Moreno-Maflas M, Pleixats R (2002) Palladium-Catalyzed Allylation with AUyl Carbonates. In Negishi E, de Meijere A (eds) Handbook of Organopalladium Chemistry for Organic Synthesis. Wiley, New York, p 1707 Larock RC, Fried CA (1990) J Am Chem Soc 112 5882 Takacs JM, Zhu J (1989) J Org Chem 54 5193 Takacs JM, Zhu J, Chandramouli SV (1992) J Am Chem Soc 114 773 Takacs JM, Chandramouli SV (1993) J Org Chem 58 7315... 

Reactions that proceed under neutral conditions are highly desirable. An important event in TT-allylpalladium chemistry is the introduction of highly reactive allylic carbonates (Sect. V.2.1.3), Their reactions can be carried out under mild neutral conditions. " Also, reactions of allylic carbamates, " allyl aryl ethers, and vinyl epoxides proceed without addition of bases. As shown by the mechanism in Scheme 6, the oxidative addition of allyl methyl carbonates is followed by decarboxylation as an irreversible process to afford TT-allylpalladium methoxide, and the generated methoxide picks up a proton from pronucleophiles (NuH), such as active methylene compounds. This in situ formation of the alkoxide is the reason why the reaction of aUyl carbonates can be carried out without addition of bases from outside. Alkoxides are rather poor nucleophiles, and alkyl allyl ethers are not formed from them. In addition, formation of TT-allylpalladium complexes from allylic carbonates involving decarboxylation is irreversible. In contrast, the formation of TT-allylpalladium acetate from allyl acetate is reversible. 

The steps of the catalytic cycle are reversible and aUyl carbonates and carbamates are obtained under carbon dioxide atmosphere (Scheme 7). ... 

Cyclic aUyl carbonates have decreased propensity to equilibrate when compared with acetates. Their reactions are stereochemically cleaner and better defined. Thus, they have been used as stereochemical probes to check the overall stereochemical outcome of the reactions. The formation of the Tf-allylpalladium(II) intermediate occurs with inversion of configuration at the allyl framework. The nucleophilic attack can occur directly on the allylic termini involving a second inversion of configuration (overall retention) or indirectly by previous attachment of the nucleophile to the Pd atom followed by reductive elimination with retention (overall inversion). The reported examples involving cyclic allylic carbonates are in Scheme 10 and Table 1. 

Judging from the reaction times and temperatures and also from the amounts of allylic substrate and SnCl2 required to obtain the aUylation products in reasonable yield, aUyl carbonate, in general, is more reactive and practical than the corresponding acetateJ In fact, methyl (Z)-4-acetoxy-2-butenyl carbonate selectively undergoes aUylation at the carbonate moiety, whereby the acetate moiety remains unchanged (Scheme 6). ... 

Substituted 3-allylindoles can also be prepared through a third procedure that is based on the reaction of o-alkynyltrifluoroacetanilides with aUyl carbonates in the presence of the Pd2(dba)3-ttmpp catalyst system in THF at 60 °C and that apparently does not involve 7V-allyl intermediates (Scheme 29). 

Formation of /3-lactones throngh these procedures is rare carbonylation of alkenyl oxiranes gives these products in low yields. AUyl carbonates may also serve as precursors to butyrolactones in a method developed by Tamaru et al. A protic solvent such as ethanol gives a ca. 1 1 mixture of the isomerized o,/3-unsaturated lactone and the acyclic ester, whereas an aprotic solvent (e.g., dioxane, THF, benzene) leads exclusively to the expected lactone (Scheme 12). 

PaUadium(n) enolate complex intermediates are also generated by the silicon-palladium exchange reaction of silyl enol ethers with 7r-allylpalladium(ll) alkoxide intermediate, which is formed in situ from aUyl carbonate with palladium-phosphine complex. With a catalytic amount of Pd(OAc)2 and dppe (diphenylphosphinoethane) in acetonitrile, silyl... 

T. Suzuki and H. Fujimoto, Inorg. Chem., 1999, 38, 370-382. Mechanisms of the Nucleophilic Substimtion of the AUyl Carbons of ( 7r-Allyl)platinum and (rr-Allylfpal-ladium Complexes. 

Nucleophilic Displacement. PhTMS-BF3 0Et2 system has been shown to be useful in the transformation of allylic alcohols to allylic sulfides (eq IS). Preparation of unsymmetrical diaryl sulfides can be achieved by reaction of arenediazonium tetraflu-oroborates with PhSTMS (eq 19). In some cases, addition of cupric sulfide increases the yield of the diaryl sulfides. The use of (phenylthio)trimethylsilane as a coupling partner in palladium catalyzed reactions with aUyl carbonates (eq 20) and aryl iodide (eq 21) has been explored. ... 

Fig. 4 Charge distribution and structures of the cyclohexadi-ene ring at the TS (color code corresponds to the atonric charges, from blue negative to ted positive). The aUyl attack conformations pre-polarize the aUyl carbon from —0.08 a.u. to about —0.17 a.ir., regardless of the attack orientation (Re or Si face). On the other hand, the conformations corresponding to the homoallyl attack prepolarize the homoallyl carbon from —0.24 a.u. to about —0.32. Relative energies of the F6 molecules are shown in parenthesis (kcal/mol, red) compared to the optimized geometry, and arrows indicate the boron attack...

In considering the stmcture of 7i-allylpaUadium cationic complexes, the nature of the charge distribution reveals that the terminal aUyl carbons are somewhat negative, whereas the central carbon is somewhat positive. For example, the complex 4 (Fig. 2) has the indicated charges on the aUyl fragment... 

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