this invention relates to crystals of compounds of formula , wherein tbs represents t - butyldimethylsilyl , and ph represents phenyl , or its salt or solvate . compounds of formula are synthesis intermediates of 2 - substituted - 1β - methyl carbapenem compounds useful as antimicrobial agents . the crystals of the present invention have excellent handleability and can realize the production of carbapenem compounds having excellent antimicrobial actibity in a simpler manner with improved yield and purity .