Stereocontrolled synthesis of all eight stereoisomers of the putative anti-androgen cyoctol

A New Synthetic Approach to High‐Purity (15R)‐Latanoprost

“…The ω chain elongation of sulfone 21 to the prostaglandin 22 initially encountered serious difficulties, mainly due to the moderate reactivity of the iodide 15 and the lability of the C(11)‐ O ‐silyl group in 21 . Based on the known behavior of alkyl or aryl sulfones,23,24 we chose the lithium hexamethyldisilazane (LHMDS)/THF conditions for the alkylation of the carbanion generated at C(13) of sulfone 21 , which eventually led to the desired substitution product 22 , albeit in a modest isolated yield of 46 %. This alkylation reaction required room temperature.…”

Stereoselective Anti‐Markovnikov Geminal Diamination and Dioxy­gena­tion of Vinylarenes Mediated by the Bromonium Ion

“…After removal of the Boc group of 3 by treatment with trifluoroacetic acid (TFA) in the presence of triethylsilane, the crude amine⋅TFA salt was directly applied to the diastereoselective intramolecular Mannich reaction. The reaction with 4‐benzyloxybutanal 4 13 proceeded to completion in 48 h in the presence of 3 equiv. of NaHCO 3 and MS 3 Å, affording the bicyclic compound 5 in 98% yield as a thermodynamic product through equilibrium via the retro‐aza ‐ Michael reaction 14.…”

Total synthesis of a protected form of sphingofungin E using the [3,3]-sigmatropic rearrangement of an allylic thiocyanate as the key reaction

“…Since the attempted desulfonation of 27 by either aluminum amalgam 14 or Li-naphthalene 6e,15 afforded unidentified products, we decided to search for more effective reaction conditions. In the end, desulfonation of 27 was achieved using 6% sodium amalgam 16 in dry methanol and resulted in the formation of the fully protected aminopolyol 28 (64%). After routine deprotection of 28 with TBAF, the resulting alcohol 29 (88%) was subsequently treated with PDC in DMF to furnish the desired a-substituted a-amino acid 30 (65%) that possessed the correct stereochemistry at all stereogenic centres (Scheme 5).…”