58469-00-4Relevant academic research and scientific papers
Boron Lewis Acid-Catalyzed Regioselective Hydrothiolation of Conjugated Dienes with Thiols
Kumar, Gautam,Qu, Zheng-Wang,Ghosh, Soumen,Grimme, Stefan,Chatterjee, Indranil
, p. 11627 - 11633 (2019)
A transition-metal-free hydrothiolation of 1,3-dienes for the synthesis of secondary and tertiary allylic sulfides is reported. The boron Lewis acids tris(pentafluorophenyl)borane, B(C6F5)3, and BF3·Et2O are shown to catalyze the regioselective hydrothiolation of a wide range of terminal 1-aryl-1,3-dienes. In the case of internal 1,3-dienes, B(C6F5)3 is by far the better catalyst than BF3·Et2O. The process features mild reaction conditions, broad scope, and low catalyst loading, and it can be scaled up quickly over a short reaction time. The reactions are rate-limited by the 1-aryl-directed protonation of 1,3-dienes with thiol-boron Lewis acid complexes, followed by sulfide anion transfer to the resultant allyl cations, as revealed by high-level DFT calculations.
Approaching the C33-C38 fragments of amphotericin B and nystatin by a retro-[1,4]-Brook rearrangement and the stereoselective manipulation of the resulting allylsilane
Gibson, Christoph,Buck, Thomas,Walker, Martina,Brückner, Reinhard
, p. 201 - 205 (2007/10/03)
Sulfide S-4 (98.6% ee) furnished allylsilane S,S-anti-2 through a potassium naphthalenide induced, highly stereoselective retro-Brook rearrangement. Treatment with diethylborane followed by NaOOH/H2O2 delivered alcohol 9 as a single diastereomer. Cylization (→10), oxidation (→16), and methylation gave ketone 17. Reduction of 17 with Et3SiH in CF3CO2H was accompanied by an unprecedented rearrangement of the neighboring oxasilolane ring to the C-silylated tetrahydropyran 20. It was oxidized to alcohol 21 which - if one inverted its OH group - would become a new C33-C38 building block for the polyol/polyene antibiotics amphotericin B and nystatin.
