Merck + Co., Inc.

Mallory F Loewe

Raymond Cvetovich

James M Balkovec

David J Mathre

George G Hazen

A stereocontrolled glycosidation with thiophenyl 4-(N-allyloxycarbonyl)-epi-methylamino-4-deoxyoleandrose and 5-O-allyloxycarbonyl avermectin B.sub.1 monosaccharide using N-iodosuccinimide produces exclusively the .alpha.-anomer of a precursor of 4'-epi-methylamino-4'-deoxyavermectin B.sub.1 in 90% yield. Deprotection and crystallization as the benzoic acid salt yields 4'-epi-methylamino-4'-deoxyavermectin B.sub.1 (emamectin benzoate), a potent insecticide.

Glycosidation route to 4'-epi-methylamino-4'-deoxyavermectin B.sub.1

A facile process for preparing a compound of the formula ##STR1## or a salt thereof, wherein R, R.sub.1, R.sub.2, R.sub.3, R.sub.4, X, X.sup.1 Y and Z are as defined in the specification, by direct phosphorylation of the corresponding phenolic compound with tetrabenzyl pyrophosphate in the presence of lithium hydroxide is described.

Process for phosphate ester compounds of certain cyclohexapeptides

A process is described for the synthesis of 3(S)-4(R)-3-[1(S)-hydroxyethyl]-4-(alkoxycarbonylmethyl)-azetidin-2-one (II) which is a useful intermediate in the synthesis of carbapenem antibiotics.

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Marlboro, NJ, United States of America

Mallory F Loewe