Studies Directed toward the Total Synthesis of Azaspiracid:  Stereoselective Construction of C<sub>1</sub>−C<sub>12</sub>, C<sub>13</sub>−C<sub>19</sub>, and C<sub>21</sub>−C<sub>25</sub> Fragments CarterRich G. WeldonDavid J. 2000 The efficient entry to the C<sub>1</sub>−C<sub>12</sub>, C<sub>13</sub>−C<sub>19</sub>, and C<sub>21</sub>−C<sub>25</sub> fragments of azaspiracid is outlined. The C<sub>1</sub>−C<sub>12</sub> portion is constructed using a key asymmetric allenyl borane addition to the corresponding α,β-unsaturated aldehyde. The synthesis of the C<sub>13</sub>−C<sub>19</sub> portion utilizes an Evans asymmetric alkylation followed by Sharpless asymmetric dihydroxylation. In addition, a novel solution to the mismatched effects of a neighboring chiral oxazolidinone during a Sharpless dihydroxylation is detailed.