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The absorption spectrum and its relative polarization, the optical-rotatory-dispersion (ORD) spectrum, and the circular-dichroism spectrum (CD) of thin benzil single crystals grown perpendicular to the optic axis, are obtained and compared in the 3000–7000- Å region. The CD spectrum shows two main bands that correspond to the absorption bands with maxima at 3325 and 3850 Å. These two bands result from transitions that are found to have similar signs for the Cotton effect, but opposite to that of the strong optically active transition at 2400 Å and responsible for the plain curve on the longer-wavelength side of the absorption edge. The bands at 3325 and 3850 Å have similar values for the dissymmetry factor g, comparable absorption intensity, and similar relative orientation of their transition moments. From the observed value of the g factor, the two bands seem to result from magnetic-dipole-allowed transitions. These observations suggest the assignment of these two bands to the two split components of the n,π* transitions resulting from the intramolecular interaction between the two carbonyl groups of the benzoyl units in the benzil molecule. The CD spectrum assists in understanding the shape of the ORD spectrum, including the minimum on the longer-wavelength side of the absorption edge, that was previously observed, but not explained. An extremely weak band is observed in the CD spectrum of thick single benzil crystals at above 4250 Å, whose origin is briefly discussed. A comparison is made between predicted polarization characteristics, using an independent-model approach, and the observed properties of the split components of the molecular n, π* transition in the crystal. The disagreement is discussed in terms of mixing between the two molecular n, π* states with each other and with the other molecular (or crystal) states.

A continuous flow incubation (perufusion) system was developed in which the secretory responses of pools of hemipituitaries from adult male rats to hypothalamic extract (HE) were characterized by serial radioimmunoassay of LH and FSH in the effluent medium. There was in initial massive release of LH and FSH which, in the absence of HE, declined to low basal levels at a rate which depended on the flow rate. Thereafter, the baseline for LH continued to decline gradually while that for FSH was stable. The rate of LH and FSH release rose abruptly after addition of the HE to the medium and returned promptly to baseline after withdrawal of the HE. During continuous infusion of HE for five hours, LH secretion was maintained at a relatively constant, elevated level. The responses to repeated identical pulses of HE were highly reproducible. The variability between responses by any one pool of tissue was significantly less than between responses of separate pituitary pools including pools comprising right and left halves of the same glands. For any given pool of pituitaries of the relationships were linear between: 1) duration of HE pulses (concentration constant) and increases in LH output, and 2) log of concentration of HE (pulse duration constant) and increases inLH and in FSH output. Consistent responses were obtained for up to 12 hr, the maximum period tested.

A new method has been developed,for the construction of the side chain of Cl , sterols from Czl-20-keto steroids and used for the synthesis of A16-and cis-A1~~*O~-cholesterol. The a,p-unsaturated nitrile 1, obtained by the dehydration of the cyanohydrin of pregnenolone acetate, was treated with isoamylmagnesium bromide to give the @,@-unsaturated ketone 3, which was isomerized to the p, y-unsaturated ketone 6 by treatment with base. The 22-keto group of 3 and 6 was then converted into the 22-methlene group by treatment of their 22-ethylene thioketal derivatives with lithium and ethylamine to give C~S -A~~( *~) -and Al6-cho1esterol, respectively. Alternatively, the enone 3 was converted into an allyl ether 22, which was then treated with lithium and ethylamine to give ~is-A~~(~o)-cholesterol. The 17-20 double bond of 3 and the 16-17 double bond of 6 has been selectively reduced to give 22-ketocholesterol, which was then converted into cholesterol via its 22-ethylene thioketal.

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