Dioxolanone intermediate useful in the synthesis of Homoarringtonine

The invention discloses 2-((2R,4 R)-4-( 4-(benzyloxy)-4-methylpent-2-yn-1-yl)-2-(tert-butyl)-5-oxo-1 ,3-dioxolan- 4-yl)acetic acid of formula (XIX), a process for its preparation and processes for its conversion into enantiomerically pure (R)-2-(2-methoxy-2-oxoethyl)-6,6-dimethyltetrahydro-2H-pyran-2-carboxylic acid of formula (I), a molecule useful for the synthesis of Homoharringtonine.