Acyclic alkenyl ether

BINAP-Ru complexes can catalyze the enantioselective hydrogenation of alkenyl ethers as shown in Scheme 1.15 [93], 2-Methyltetrahydrofuran with 91% ee and 87% ee can be synthesized by BINAP-Ru-catalyzed hydrogenation of 2-methylenetetrahydrofuran and the endo-type substrate, 2-methyl-3,4-dihydrofuran, in CH2C12 under 100 atm of hydrogen, respectively. With the same Ru complex, phenyl 1-phenylethyl ether, an acyclic alkenyl ether, is reduced in a moderate optical yield. 

Perfluoroallyl fluorosulfate is prepared by the treatment oiperfluoropropene with sulfur tnoxide m the presence of boron catalysts [2, 3, 4, 5, 6, 7] (equation 2) Perfluoroisopropyl allyl ether reacts similarly to give 58% polyfluoroallyl fluorosulfate in a cis/trans ratio of 6 4 [S] Sultones are the exclusive products without catalyst. Polyfluoroolefins such as 2-hydropentafluoropropylene [9], (2,3-dichloropropyl)tri-fluoroethylene [70], perfluoropropene [2, i], perfluoroisopropyl alkenyl ethers [S], and acyclic polyfluoroallyl ethers [77] undergo sulfur trioxidation to regioselectively produce the corresponding P-sultones in high yield... 

As the representative examples in Scheme 6.11 illustrate, similar stragies may be applied to the corresponding alkenyl ethers (vs. styrenyl ethers) [26], The Zr-catalyzed kinetic resolution/Ru-catalyzed metathesis protocol thus delivers optically pure 2-substituted di-hydrofurans that cannot be accessed by resolution of the five-membered ring heterocycles (see Scheme 6.8). It should be noted, however, that the efficiency of the Zr-catalyzed resolution is strongly dependent, and not in a predictable manner, not only on the presence but the substitution of the acyclic alkene site of the diene substrate. The examples shown in Scheme 6.11 clearly illustrate this issue. 

The successful use of the silver complex formed from an iso-leucine-derived phosphine (L2 in Scheme 11.4) as catalyst for the multicomponent Mannich reaction of silyl enol ethers 10 with in situ formed aliphatic imines allowed its application in the enantioselective synthesis of the alkaloid sedamine (56% yield, 98% ee) [17]. Also cyclic and acyclic alkenyl trichloroacetates (10, Z = EtOCO) can be used in the reaction with ethyl glyoxylate and diverse aniline derivatives 11 catalyzed by... 

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