Daewoong Pharmaceutical Co., Ltd.

Ace Antenna Corporation

Jae Ho Lee

Chi Jang Moon

Sea Han Oh

Jung Kun Oh

Yong Hee Lee

Joon Wan Kim

Kyung Up Baik

Byung Ill Oh

Jung Sik Kim

A antenna system of the present invention comprises a radiator for radiating a radio frequency, which is converted from electric power, and which has a impedance matching unit and a power divider; a first reflector for reflecting and filtering the radio frequency; and at least one second reflector for filtering the radio frequency radiated in the sideward direction of the antenna system, which is vertically attached to the first reflector, and is able to be moved in a horizontal direction.

Antenna system having a choke reflector for minimizing sideward radiation

The present invention relates to a novel and improved process for preparing 4-acyloxy-2-azetidinone derivatives having the following formula (I) which are useful as an intermediate for synthesis of penem or carbapenem compounds: ##STR1## in which R.sub.1 represents a hydroxy-protecting group; and R.sub.3 represents an acyl group, which comprises reacting an azetidinone derivative having the following formula (II): ##STR2## wherein R.sub.1 is defined as above and R.sub.2 represents an alkyl group or an aryl group, with a N-haloacylimide in the presence of an organic carboxylic acid or a salt of an organic carboxylic acid. The present invention uses the organic compound, N-haloacylimide, as the reactant rather than the heavy metal reactant used in the prior art, and thus provides an economical advantage and does not cause any problem related to safety and waste disposal after the reaction.

Acyloxylation process for preparing 4-acyloxy-2-azetidinone derivatives

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Kyunggi-do, South Korea

Jae Ho Lee