An efficient synthesis of (3R,4R)-3-(1-(R)-hydroxyethyl)-4-(benzoyloxy)-2-azetidinone from L-threonine. Use of phenylalkoxymethyl as a novel N-protecting group
Preparation of azetidinones via N-protected oxirancecarboxamide
申请人:Schering Corporation
公开号:US04740595A1
公开(公告)日:1988-04-26
A multistep process is disclosed for preparing azetidinone intermediates used in the making penems and carbapenems wherein intermediates containing ##STR1## R' is independently hydrogen or 1, 2 or 3 of lower alkyl or lower alkoxy, preferably hydrogen, wherein R" is methyl, ethyl, a phenyl or alkyl, preferably ethyl, as a readily removable nitrogen protecting group are made.
Preparation of azetidinones via novel protected intermediates
申请人:Schering Corporation
公开号:US04963670A1
公开(公告)日:1990-10-16
A multistep process is disclosed for preparing azetidinone intermediates used in the making penems and carbapenems wherein intermediates containing ##STR1## R' is independently hydrogen or 1, 2 or 3 of lower alkyl or lower alkoxy, preferably hydrogen, wherein R" is methyl, ethyl, a phenyl or alkyl, preferably ethyl, as a readily removable nitrogen protecting group are made.
In this study, we developed a new approach for the solid-phase synthesis of oligodeoxynucleotides (ODNs) using nucleobase-unprotected oxazaphospholidine derivatives. We tackled the problem of the difficult purification of N-unprotected monomers due to their high affinity to silica gel by introducing a tetrahydrogeranyl group into the oxazaphospholidine monomers, thereby enhancing the lipophilicity