cis-dienylborane (the C10–C22 part) with the trans vinyl iodide corresponding to the C1–C9 part. The stereogenic centers at C7 and C14 were created by Ru-catalyzedasymmetricreduction of ketone and asymmetric epoxidation/kinetic resolution of the racemic alcohol, respectively.
The synthesis of enantiomerically pure 2,5-disubstituted 3-oxygenated tetrahydrofurans has been achieved from cheap and commercially available l-malic acid. This method was used to prepare an advanced intermediate toward CMI-977, a promising candidate for the treatment of chronic asthma. furan - tetrahydrofuran - singlet oxygen - butenolide - oxacycles - natural products