A Versatile Route to the Tulearin Class of Macro Lactones: Synthesis of a Stereoisomer of Tulerarin A
Alexander L. Mandel, Veronique Bellosta, Dennis P. Curran and Janine Cossy.
Link to the PDF

Here is a fun little paper out of Paris. This paper really makes up for the lack of reactions you saw in the last paper, totaling about 18 (some being deprotections and protections hence the about).

The science begins with a Julia Kocienski Olefination. Here they used a Sulfone with a phenyltetrazolyl group on it to bring forth the trans alkene. The mechanism involves potassium bonding to the non conjugated carbon adjacent to the sulfone and an attack on the aldehyde. Then after a series of elimations it gives off sulfur dioxide and the phenyltetrazolyl.

After the Sharpless they used DIBAL-H to reduce the ester within the lactone into an aldehyde and then they used a methyl phosphine to afford the terminal alkene, which becomes very important later in the synthesis.

Here they used a benzylthiazolidine thione group, known as the Crimmins Chiral Auxiliary, with specific conditions in this aldol addition to attain specific stereochemistry. After that they do a simple protection and then remove the benzylthiazolidine thione group using hydroxide and peroxide.

Finally, completing the scaffolding, they carry out a ring closing metathasis using Grubbs first generation. They also attempted the reaction using other catalysts, but gave side products or did not react at all.

Some nice science, liked the Julia and seeing the Crimmins in action was nice.