Epoxyalkyl groups

A vej atile procedure for the introduction of alkyl, epoxyalkyl groups into heterocycles, which Involves displacement of leaving groups by Wittig reagents, followed by appropriate manipulation of the resulting ylides, has been applied to the synthesis of various 6-substl ted purines designed as inhibitors of adenylsuccinate synthetase and lyase. 

The protocol has been applied to the addition of epoxyalkyl groups (Eq. 68), which would give rise to severe difficulties with the usual organometallic methods. Additions proceed in good yields with preservation of the epoxide ring,304 when at least 3 carbons separate the functionalities. This result provides further evidence of a radical mechanism a carbanionic species would probably open the 3-membered ring intra- or intermolecularly. 

Despite a higher intrinsic reactivity, epoxides of type 35 and 36 show a lower inactivation rate kj(max), as seen in Table XI, than the conduritol epoxides. This is probably caused by the greater flexibility of the epoxyalkyl chain in the active-site cleft, and by non-productive binding in positions where the oxirane is not within reach of the catalytic groups of the active site. For epoxypropyl oligosaccharides, this would hold even when the inhibitor occupies the correct subsites. 

The conversion of oxiranes containing various functional groups has been studied with organolithium compounds. /3-Substituted allyl alcohols are formed stereoselectively with -butyl-lithium from 1,2-epoxyalkyl phosphonates (Eq. 

The ring opening of epoxyalkyl radicals, unlike that of cyclopropanecarbinyl radicals, usually proceeds with cleavage of the cxo-cyclic carbon-oxygen bond of the epoxides. However, a substituent group that stabilizes the radical produced by... 

However, preservation of the functional group Y was found to be successful only for 2-chloroethyltriethoxysilane and benzyltriethoxysilane. In the corresponding IR spectra of PSLs modified with alkenyl- and epoxyalkyl-fimctionalized silanes the characteristic absorptions of the olefinic or the oxiiane group are not detectable. 

The asymmetric alternating copolymerization of olefin and CO has been achieved by using chiral ligands Me-DUPHOS and BINAPHOS for the functionalized olefins possessing hydroxyl, carboxy, carbamate, amide, fluoroaryl, epoxyalkyl,perfluoroalkyl, and para-chlorophenyl groups (Figure 10). 

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