Mukaiyama aldol coupling of the second-generation C1C14 (AB) fragment of altohyrtins (spongistatins) with the model α-methyl-β-alkoxyaldehydes revealed that the stereochemistry at the newly formed carbon centers was controlled by the β-alkoxy chiral center of the model aldehydes. The union of the AB fragment with the C15C28 (CD) fragment under the same conditions gave the fully elaborated C1C28 (ABCD)