Saturated epoxides

Asymmetric ring-opening of saturated epoxides by organoctiprates has been studied, hut only low enantioselectivities f -c 1596 ee) have so far been obtained [49, 50]. Muller et al., for example, have reported that tlie reaction between cyclohexene oxide and MeMgBr, catalyzed by 1096 of a chiral Schiffhase copper complex, gave froiis-2-metliylcyclohexanol in 5096 yield and with 1096 ee [50]. 

The monomer (laurolactam) could he produced from 1,5,9-cyclododeca-triene, a trimer of hutadiene (Chapter 9). The trimer is epoxidized with peracetic acid or acetaldehyde peracetate and then hydrogenated. The saturated epoxide is rearranged to the ketone with Mgl2 at 100°C. is then changed to the oxime and rearranged to laurolactam. 

A new analytical method [34] for the enantiomeric purity of epoxide pheromones as well as a new method [35] for stereochemical inversion of saturated epoxides were reported by Oliver. 

The formation of the product by attack at the secondary carbon atom was not due to a concurrent S 1 reaction since the isomer ratio was not affected by changes in methoxide ion concentration. Saturated epoxides differ from this example in that bimolecular attack always takes place at the less substituted carbon atom. 

Conversion of epoxides (arene oxides) into phenols is spontaneous. The conversion of epoxides into dihydrodiols is catalyzed by EH (EC 4.2.1.63). Hydroxyl containing PAHs can act as substrates for conjugases (C) (UDP glucuronsyl transferase (EC 2.4.1.17) and phenol sulphotransferase (EC 2.8.2.1)). This pathway usually leads to inactive excretable products. Epoxides are scavenged by GSH and the reaction is catalyzed by GSHt (EC 2.5.1.18). When GSH is depleted and/or the other pathways are saturated, epoxides of dihydrodiols (particularly 7,8-diol-9,10-epoxides in the case of BP) and phenol metabolites react with cellular macromolecules such as DNA, RNA, and protein. If repair mechanisms are exceeded the detrimental effects of PAH may result. 

Saturated epoxides are opened in good yield by lithium dimethylcuprate.33 The methyl group is introduced at the less hindered carbon of the epoxide ring. 

Addition of hydroahlorio acid or by tf robromic add to 1,2-epoxv -3 butene (Eq. 710) is reported to give only 2-ohloro- and 2-broroo-3-buten-l-ol respectively. 1381 The decisive influence exerted by tin-double bond is evident, when it is recalled that the corresponding saturated epoxide is opened in the opposite sense. 

When saturated epoxides such as propylene oxide react with hydrogen halides, the dominant mode of reaction introduces halide at the less-substituted primary carbon (anti-Markovnikov). ... 

Examination of the literature confirmed that acid or basic type catalysts can catalyze the reaction of alcohols with oxirane (epoxy) groups. However, the reported studies dealt only with saturated epoxidized compounds and low molecular weight alcohols primarily in an attempt to define... 

TMO Copolymerization With Saturated Epoxides. Copolymerizing TMO with ethylene oxide (EO) in an 80 20 weight ratio with the chelate catalyst gave a water-soluble product (90% of the total) which contained only 8% TMO (Run 2, Table II). On the basis of an ideal copolymerization, the EO is estimated to enter the copolymer in this fraction approximately 70 times more readily than does the TMO. This result confirms that alkylene oxides polymerize much more readily than oxetanes with the chelate catalyst. A small amount (10% of the Total) of a water-insoluble copolymer containing 44% TMO was obtained. This result indicates that the chelate catalyst contains some sites which give more favorable copolymerization. One possible explanation is that the unfavorable copolymerization of TMO at the major sites is due to steric hindrance which reduces the ability of TMO to coordinate at this site. 

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