Aldehydes and Ketones with Benzyl Alcohols and Amines 1875 acetone' and oxygen was bubbled through the solution for three days, acetone being added from time to time to replace that lost by evaporation. The solvent was evaporated and the solid residue extracted with a solution of potassium bicarbonate. Acidification of the carbonate solution, however, yielded no organic acid. Extraction of the residue with 5% sodium hydroxide yielded isodurenol melting at 78-79°.7 The only compound which (7) Hey, J. Chem. See., 1590 (1931). was isolated from the neutral fraction was unchanged enol (4.4 g.

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A model for a biologically active conformation of somatostatin is proposed. This model is based primarily on the biological results obtained with novel bicyclic somatostatin analogs having a covalent bridge replacing the side chains of residues 5 and 10, 6 and 11, and 5 and 12, respectively, rather than on physical measurements on the hormone in solution. The high activity of an analog in which Phe6 and Phe11 are replaced by cystine provides evidence that these phenylalanines stabilize the biologically active conformer through "hydrophobic bonding" but do not directly interact with the receptor. The synthesis of the novel bicyclic analogs of somatostatin and the effects of these on the inhibition of secretion of insulin, glucagon, growth hormone, and gastric acid are described.

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