Introduction of cis-vicinal amino alcohol functionality into the cyclohexane ring employing (1S,2S)-2-amino-1,2-diphenylethanol: synthesis of enantiopure aminocyclohexitols

Facile, Efficient, and Enantiospecific Syntheses of 1,1‘-N-Linked Pseudodisaccharides as a New Class of Glycosidase Inhibitors

“…Palladium-catalyzed coupling reaction of allylic choride 13 with amine 15 using TMPP as the ligand proceeded smoothly at room temperature, affording the desired pseudodisaccharide 16 in 78% yield and the undesired diene 17 in 15% yield. Other protecting groups (acetate, carbamate, and MOM) at C-2, which are shown in Table , were examined but gave inferior yields (42−57%) of the disaccharides with increased amounts of the corresponding diene (24−38%).…”

Enantiospecific Synthesis of Pseudoacarviosin as a Potential Antidiabetic Agent

“…Palladium-catalyzed coupling reaction of allylic chloride 8 and amine 9 produced a pseudo-1,4-aminodisaccharide in 84% yield. Three equivalents of amine 9 were required in order to give good yields of the adduct, and fortunately, most of the excess amine 9 was recovered.…”

“…Three equivalents of amine 9 were required in order to give good yields of the adduct, and fortunately, most of the excess amine 9 was recovered. Our previous work has already optimized the reaction conditions on similar substrates and reported that acetal blocking groups were ideal for this type of reaction that proceeded with retention of configuration. The 1 H NMR spectrum of 23 displays J 1,2 = 5.1 Hz and J 2,3 = 10.8 Hz, indicating that H 1 and H 2 are still cis -disposed after the coupling reaction and the structure is therefore assigned as protected pseudoacarviosin 23 .…”

An Enantioselective Total Synthesis of (−)‐Isoschizogamine

“…The presence of an acid additive is essential to ensure areproducible yield of 21.A mong av ariety of Lewis acids (AgBF 4 , Al 2 O 3 )a nd Brønsted acids (TFA, HOAc,C lCH 2 COOH, Cl 2 CHCOOH, PhCOOH, tBuCOOH) examined, pivalic acid gave the best results.T he two C14 epimers of 21 were separable and were fully characterized. However,amixture of two epimers was used for the next step for the sake of convenience.O xidation of 21 to the selenoxide (NaIO 4 in methanol buffered with aqueous NaHCO 3 ), [20] followed by a syn elimination in MeOH/1,2-dichloroethane in the presence of Na 2 S 2 O 3 and diethyl amine,a fforded (À)-isoschizogamine [(À)-1]a st he only isolable product in 46 %y ield. We note here that natural product (À)-1 with the double bond distal to the nitrogen atom was the only regioisomer isolated from the reaction mixture.…”

“…However, a mixture of two epimers was used for the next step for the sake of convenience. Oxidation of 21 to the selenoxide (NaIO 4 in methanol buffered with aqueous NaHCO 3 ),20 followed by a syn elimination in MeOH/1,2‐dichloroethane in the presence of Na 2 S 2 O 3 and diethyl amine, afforded (−)‐isoschizogamine [(−)‐ 1 ] as the only isolable product in 46 % yield. We note here that natural product (−)‐ 1 with the double bond distal to the nitrogen atom was the only regioisomer isolated from the reaction mixture 21.…”