The construction of the fragments C-1-C-9 3 and C-17-C-27 4a of the br
yostatins in a enantioselective and highly diastereoselective fashion
is described, The usefulness of the ''chiron'' approach is illustrated
with the synthesis of these fragments from respectively D-pantolacton
e (6) and D-isobutyl lactate (14) as chiral templates.