A concise and efficient carbohydrate-based approach for the total syntheses of (+)-garvensintriol and (+)-5-epi-garvensintriol is described in nine and six steps with 20% and 37% overall yield, respectively, starting from a known intermediate. A sequence of Grignard-assisted lactol opening with terminal alkyne, stereoselective keto reduction and oxidative lactonization are the key reactions.