Slight changes in the chemical shifts of protons in 3,4-dehydroproline derivatives cause the appearance of their proton magnetic resonance spectra to change markedly, and this can be effected by taking one compound in two different solvents or by observing closely related derivatives in the same solvent. The explanation involves a previously undescribed type of deceptively simple coupling and the necessary conditions are discussed. A first-order analysis of the ABMXX' pattern for 3,4-dehydroprolinamide in deuterium oxide is given. A full analysis is made of the ABXX' and ABXY patterns for this amide in deuterium oxide and deuterochloroform respectively after deuterium exchange of the labile H2; a very large homoallylic coupling is required. Two conformations exist at 40� in solution for all N-benzyloxycarbonyl methyl esters of proline and its derivatives due to restricted rotation about the amide bond. Free rotation of the amide bond of corresponding N-acetyl and AT-benzoyl derivatives still occurs at -50�. The deceptively simple spectrum of N-benzyloxycarbonyl-2,5-dihydroxy-Δ3-pyrolne is discussed and that of its diacetate is analysed as an A2X2 system; a very small homoallylic coupling is required.

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The 39K(n,y)40K reaction has been studied using a Ge(Li) and a Ge(Li)-Ge(Li) spectrometer. A total of 252 gamma-ray transitions has been observed and a gamma-gamma coincidence matrix involving 62 transitions has been established. A decay scheme based on the experimental results is deduced for 202 of the observed gamma-ray transitions. Spins and parities of some excited states have been estimated from the deduced branching ratios. The neutron separation energies of the 40K and 42K nuclei have been determined as 7800.5 + 0.2 and 7535.2 _+ 1.5 keV respectively.

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