Problems and exercisesThe synthetic equivalent

Which synthons are the following the synthetic equivalents of: a) 1-methoxyvinyllithium, CH₂=C(OMe)Li; b) lithium bis(1-methoxyvinyl)cuprate; c) 2-lithio-2-phenyl-1,3-dithiane?

Propose synthetic equivalents for the synthons ⁻CH₂COCH₃ and ⁺CH₂CH₂OH, and use them to prepare 5-hydroxypentan-2-one.