1: methanephosphonic acid dimethyl ester With n-butyllithium in tetrahydrofuran; hexane T=-78°C; 2: (3S,4S,8R)-6,6-dimethyl-3-methoxy-2,5,7-trioxobicyclo[3.3.0]octanone in tetrahydrofuran; hexane T=-78 - -20°C; 2.83333 h; Further stages.;