Chiral alkenes spectra

It will help at this point to realize that the molecule consists of three spin systems with the insulation point at C-6 (see Section 3.5.2). The alkyl system consists of H-l, H-2, H-3, H-4, H-5, and H-9 an alkene system consists of H-7 and H-8 and another alkene system consists of H-10. The alkyl system accounts for the multiplets at the right of the spectrum, and the alkenes account for the multiplets at the left side. It will also help to reiterate that the protons of an alkyl CH2 group will be diastereotopic in the presence of a chiral center. As will be the protons of an alkene=CH2 group. 

In contrast to SMOs, which exclusively catalyze the formation of (S)-epoxides, CPOs are able to yield chiral (P)-epoxides from styrene derivatives, which could serve as a stereocomplementary method (Scheme 13.11). However, the substrate spectrum appeared to be very limited [85,109]. Two ds-disubstituted aryl-substituted alkenes, czs-a-methylstyrene and 1,2-dihydronaphthalene, were effectively epoxi-dized in the presence of H Oj, and the later underwent spontaneous hydrolytic ring opening to afford the corresponding trans-diol. The enantiomeric excesses of the products were as high as 96% and 97% ee, respectively [83]. Terminal alkenes such as styrene and derivatives with a halide substituent on the benzene ring [109] or an alpha-alkyl substituent [85] could be accepted by CPO, and underwent epoxidation using f-BuOOH or HjOj as the oxidant, but the (P)-epoxides were achieved with only low to medium enantiopurity [83,85,109]. 

A series of covalent 96 and ionic 97 platinum complexes with chiral amine hgands (Figure 50.27) are effective chiral discriminating agents for alkenes and allenes. The substrate displaces the ethylene, and the Pt NMR spectrum is used for the determination of enantiomeric purity. Whether to use the ionic or covalent complex, and which amine hgand to use, depends on the substrate. Recommendations for the optimal reagent for different classes of substrates have been summarized in prior reports. ... 

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