New Stereoselective Route to the Epoxyquinol Core of Manumycin-Type Natural Products. Synthesis of Enantiopure (+)-Bromoxone, (−)-LL-C10037α, and (+)-KT 8110

Abstract

A practical route is decribed for the preparation of the C(7)N core of manumycin-type compounds. Starting from p-benzoquinone, optically pure compounds in both forms can be prepared via enzymatic resolution of a derived diacetoxy conduritol. A diepoxy aminoinositol is accessible which can function for formation of enantiopure epoxyquinones and quinols. Examples are given for acylation reactions of this amine with several acyl derivatives. With this approach (-)-LL-C10037alpha and quinones such as (+)-KT-8110 with 5R,6S-configuration can be synthesized through oxidation. In addition a short route to (+)-bromoxone is described. Most steps include simple epoxide formation and cleavage reactions which all can be carried out in a high stereoselective manner.

Flexible Stereo‐ and Regioselective Synthesis of myo‐Inositol Phosphates(Part 1): Via Symmetrical Conduritol B Derivatives

“…Only distilled solvents were used. The building blocks (+)-and (-)-2, (-)-and (+)-3, and their precursors were prepared according to literature methods, [10,11] as were 1,4-di-O-benzylconduritol B (14) [12] and 1,4-bis(di-O-benzylphospho)conduritol B (17). [11] Purification and Analysis of Inositol Tris-and Tetrakisphosphates (HPLC-MDD): Inositol phosphates were purified and analyzed by the HPLC-MDD method described previously.…”

“…The known diacetoxydibromocyclohex-5-enes (+)-3 and (-)-3 [or the corresponding diols (-)-and (+)-2] were used as the enantiomerically pure building blocks [10,11] for the synthesis of all the myo-inositol derivatives described. Racemic 3 can easily be prepared from p-benzoquinone in three steps and 70 % overall yield.…”

Flexible Stereo‐ and Regioselective Synthesis of myo‐Inositol Phosphates(Part 2): Via Nonsymmetrical Conduritol B Derivatives

“…Only distilled solvents were used. The building blocks (+)- [11,21,22] (+)-6, (-)-6, [20,21] and their precursors, were prepared according to literature methods.…”

“…[20,21] ) was taken up in CH 2 Cl 2 (500 mL) and the organic solution washed twice with brine and dried with MgSO 4 . The MgSO 4 was filtered off, and the filtrate was put in a 1-L round-bottomed flask.…”

Reactivity versus Stability of Oxiranes under Palladium‐Catalyzed Reductive Conditions

“…[48] According to the authors, the debenzylation occurred first, which was followed by attack of the alcohol onto the oxirane. The possible stability of oxiranes towards hydrogenolysis by using supported Pd catalysts in alcoholic solvents is also illustrated in Equations (17) [49] and (18). [50] The semihydrogenation of a CϵC bond by using Lindlar's catalyst, eventually with quinoline as an additive, is also compatible with the presence of an oxirane [Equation (19)].…”