The IR spectra of methanol as a dilute solution in and in the vapour phase have been measured between 2500 and 4000 CCl 4 cm~1 and between 1000 and 1100 cm~1 in order to better understand the nature of the hydrogen bonding equilibria present. The integrated absorption coefficient of the monomeric OwH stretching mode is calculated as (2.157 ^0.025) ] 104 m mol~1 and the proportion of the components associated with the three principal bands and a fourth weaker band estimated. Seven possible components were considered which were monomer, closed cyclic and open chain dimers, trimers and tetramers. Ab initio calculations were carried out on these components using six basis sets up to the restricted Hartree Fock 6-311]]G(3df,3pd) level. Relevant calculated infrared wavenumber and intensity values, OwHÉ É ÉO bond lengths and hydrogen bonding energies are reported. The cyclic dimer is shown to be a transition state with the open dimer forming a stable minimum energy form. In the case of the trimer and tetramer the hydrogen-bonding energy is calculated to be, respectively, 12 and 32 kJ mol~1 greater in the cyclic form than in the open form with good agreement at the RHF6-31G(d) and RHF 6-31]]G(d,p) levels. The e †ect of basis set superposition errors are found to be relatively small. The experimental and theoretical results are consistent with an equilibrium involving monomer, open dimer, cyclic trimer and cyclic tetramer.

Methyl 2,5-dimethyl-4-[2-(phenylmethyl)benzoyl]-1H-pyrrole-3-carboxylate, FPL 64176 (1), is the first example of a new class of calcium channel activator (CCA) that does not act on any of the well-defined calcium channel modulator receptor sites, as typified by verapamil, diltiazem, and the dihydropyridines. The potent activity of 1, having the 2-(phenylmethyl)benzoyl substituent, was predicted using QSAR on an initial set of less potent benzoylpyrroles. When compared to the CCA Bay K 8644, 1 has similar potency on calcium uptake into GH3 cells (both have EC50 approximately 0.015 microM) but is appreciably more potent functionally at increasing contractility in a guinea pig atria preparation (1 has EC50 = 0.049 microM vs Bay K 8644 EC50 = 1.95 microM). 1 is an achiral, pharmacologically clean agonist with no demonstrable partial agonist properties and possesses appreciably higher efficacy than Bay K 8644. It should therefore become a useful biochemical and pharmacological tool for the study of calcium channels in many cell types.

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The total synthesis of precalciferol, has been effected without the use of photochemical methods. 9a-Chloro-des-AB-cholestan-8-one {5ct-chloro-l p-[(I 8 ) -I ,5-dimethylhexyl]-7a~-methyl-trans-perhydroindan-4-one) (1 ; X = a-CI) t and (1 S)-3-ethynyl-4-methyIcyclohex-3-en-l-ol (2 ; R = H) were combined to give the chlorohydrin (3; X = a-CI), which was transformed, first into the dienyne (4) and then, by semihydrogenation of the acetylene link, into precalciferol, (5). Model experiments, bearing on this and related routes to the pre-vitamin, are described.