RMgX/Rli OH CH2O R OH R2 ri R2 R 2 ROH R OH H OR R18 OH R -OH R R1 OR R R1CHO- OMaX R°oH RMgX R R Oo MaX OH RMgX R OR R OR R RRMgX/RLi + CH2O R1CHO O R OH R OH R OH R1 O R1 R OH R1 R1 R2 O R2 R R1 OH O R OH H OR2 R O R1 OR2 R1 R R OH O R' RMgX O R' Mg R X R' R OMgX R' OR'' O RMgX R' OR'' O MgX R' R OH R R R' R O