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Alkylation reactions using alpha-halolactams or lactam enolates derived from bicyclic lactam templates can proceed with high endo- or exo- diastereoselectivity respectively. In the latter case, stereochemical correction by means of enolate generation and hindered phenol quench is possible with moderate efficiency. This protocol has been applied to the synthesis of protected penmacric acid and its analogues.

Metal Replaced HemoproteinsA review with introductory laboratory preparation of cobaltmyoglobin It is clear that great progress is being made in the molecular level understanding of many of the fascinating processes of living organisms. Much of this progress has come through separation and examination of components by application and extension of modern chemistry. Among the exciting areas of comparatively recent development are the coding of protein amino acid sequences by the DNA polynucleotides, the structure and function studies of cell membranes with the very interesting transport of ions through the phospholipid bilayer, the extensive detail of many enzyme structures and the chemistry of their highly selective mechanisms as revealed in atomic detail through X-ray crystallography, magnetic resonance, or impressive chemical modification of individual residues, bioenergetics of muscle tissue, etc,, etc. Initially, much of the chemical work on enzymes depended upon natural variations among mutants or species. More recently, chemical modification of specific residues has contributed much to knowledge of binding sites and mechanisms. Another method of chemical modification in those cases where metal ions play a crucial role in the function of the molecule is to replace the metal. For metal activated enzymes such as carboxypeptidases, enolases, or phosphatases, the native metal may be re-

A Convenient Method for the Preparation of Aryl Cyclopropyl Ethers from Phenols.-Reaction of phenols (I) with cyclopropane (II) gives the aryl 1'-(phenylthio)cyclopropyl ethers (III). They can be easily desulfurated by two different methods to yield the desired aryl cyclopropyl ethers (IV). -(HOLLINGWORTH, GREGORY J.; DINNELL, KEVIN; DICKINSON, LAURA C.; ELLIOTT, JASON M.; KULAGOWSKI, JANUSZ J.; SWAIN, CHRISTOPHER J.; THOMSON, CHRISTOPHER G.; Tetrahedron Lett. 40 (1999) 13, 2633-2636; Merck Sharp Dohme Res. Lab., Neurosci. Res. Cent., Harlow, Essex CM20 2QR, UK; EN)