Bromide and iodide anions switch hydrogen-bonding patterns in otherwise isostructural dimethanol solvates N-methyl-1,4-diazabicyclo[2.2.2]octanium bromide (dabcoCH3Br·2CH3OH) and analogous iodide (dabcoCH3I·2CH3OH), both synthesized in the high-pressure version of the Menshutkin reaction at 1.2 and 2.4 GPa, respectively. The magnitudes of the high pressure triggering these reactions correspond to identical molecular volumes of both solvates.
This invention is directed to carbacephems and methods for their preparation: ##STR1## In the foregoing formulae, R.sup.3 represents phenyl, C.sub.1 -C.sub.4 alkylphenyl, halophenyl, C.sub.1 -C.sub.4 alkoxyphenyl, naphthyl, thienyl, furyl, benzothienyl, or benzofuryl.
Methods and compounds for the preparation of carbacephems
申请人:Eli Lilly and Company
公开号:US05521307A1
公开(公告)日:1996-05-28
A chiral process for preparing compounds of the formula: ##STR1## from a compound of the formula: ##STR2## in which the compound formula (IV) is reacted with trimethylsilyl iodide to remove the chiral auxiliary at the 7-position and the carboxy protecting group. The process allows for the retention of the amino and carboxy protecting groups throughout the preparation of Compound IV. Also disclosed are novel intermediates.