Dithioesters, chiral, reactions

The aldol reaction of dithioester enethiolates has been used for the synthesis of dithiolactones [123], chiral substrates for the Claisen rearrangement [124, 125], and oxathianes [126]. Thioamide enethiolates may be employed in this reaction as well as shown with /Tthiolactams [26], or with a precursor of the antitumour agent vinblastine [127]. 

Tin (II) enolates have been widely used by Mukaiyama and coworkers in aldol and Michael reactions. These enolates are generated by action of Sn(OTf)2 on ketones, esters, N-acy -1,3-oxazolidin-2-ones or -l,3-thiazolidin-2-thiones, thi-olesters or dithioesters in the presence of chiral diamines 2.13 (R = CH2NHAr or CH2N(CH2)5) bearing the (S)-proline skeleton [253, 559, 682]. Diastereoiso-meric and enantiomeric excesses observed in these reactions are often excellent. 

A review of the asymmetric thia-Diels-Alder reactions of chiral dithioesters with dienes has been published. The asymmetric organocatalytic thio-Diels-Alder reac- 0 tion of thiocarbonyls with a-methylene carbonyl dienes produced dihydrothiopyrans in high yields and high to excellent selectivities. The inverse-electron-demand 0 hetero-Diels-Alder cycloadditions of norbomene (106) with 5-benzylidene-2-arylimino-3-aryl-thiazolidine-4-thiones (107) at 25 °C produced cycloadducts (108)... 

Dithioesters bearing a chiral auxiliary have been used in asymmetric thia-Diels-Alder reactions with acyclic 1,3-dienes to produce cycloadducts with a diastereomeric excess of 90%. A Cu(II)bis(oxazoline)/dithioesters complex has been proposed to rationalize the chiral induction ... 

---