The organocatalytic one-pot oxidative cleavage of terminal 1,2-diols to one-carbon-unit-shorter carboxylic acids is described. The combination of 1-Me-AZADO (cat.), NaOCl (cat.), and NaClO(2) caused smooth one-pot oxidative cleavage under mild conditions. A broad range of substrates including carbohydrates and N-protected amino diols were converted without epimerization. Terminal triols and tetraols respectively underwent cleavage of their C-2 and C-3 moieties to afford their corresponding two- and three-carbon-unit-shorter carboxylic acids.
Irciniastatin A (a.k.a. psymberin) and irciniastatin B are members of the pederin natural product family, which have potent antitumor activity and structural complexity. Herein, we describe a full account of our total synthesis of (+)-irciniastatin A and (-)-irciniastatin B. Our synthesis features the highly regioselective Eu(OTf)3-catalyzed, DTBMP-assisted epoxide ring opening reaction with MeOH, which enabled a concise synthesis of the C1-C6 fragment, extensive use of AZADO (2-azaadamantane N-oxyl) and its related nitroxyl radical/oxoammonium salt-catalyzed alcohol oxidation throughout the synthesis, and a late-stage assembly of C1-C6, C8-C16, and C17-C25 fragments. In addition, for the synthesis of (-)-irciniastatin B, we achieved the C11-selective control of the oxidation stage via regioselective deprotection and AZADO-catalyzed alcohol oxidation. The synthetic irciniastatins showed high levels of cytotoxic activity against mammalian cells. Furthermore, chemical footprinting experiments using synthetic compounds revealed that the binding site of irciniastatins is the E-site of the ribosome.
Highly regioselective intramolecular aminolysis of 3,4‐epoxy amines has been achieved. Key features of this reaction are (1) chemoselective activation of epoxides in the presence of unprotected aliphatic amines in the same molecules by a La(OTf)3 catalyst and (2) excellent regioselectivity for anti‐Baldwin 5‐endo‐tet cyclization. This reaction affords 3‐hydroxy‐2‐alkylpyrrolidines stereospecifically in high yields. DFT calculations revealed that the regioselectivity might be attributed to distortion energies of epoxy amine substrates. The use of this reaction was demonstrated by the first enantioselective synthesis of an antispasmodic agent prifinium bromide.
A concise, protecting-group-free synthesis of the antipsychotic agent ( )-nemonapride has been achieved featuring a europium(III) trifluoromethanesulfonate (Eu(OTf) 3 )-catalyzed C4 selective aminolysis of a 3,4-epoxy alcohol by benzylamine and an expedient use of the resulting 4-benzylamino-1,3-diol product for constructing the pyrrolidine skeleton.
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