Concise diastereoselective synthesis of calcaripeptide C via asymmetric transfer hydrogenation/Pd-induced chiral allenylzinc as a key reaction

Abstract

Synthesis of the natural product calcaripeptide C derived from the fungal metabolite mycelium KF525 of Calcarisporium sp. has been achieved. This complementary approach avoids the use of a stoichiometric amount of chiral auxiliary reagents as commonly used to generate enantioenriched advanced precursors. The enantioselective synthesis of calcaripeptide C is remarkable in that using catalytic reactions sets the two stereogenic centers efficiently with good levels of enantioselectivity. Further diversification of the calcaripeptide C structures is possible by employing a complementary catalytic enantioenriched Ru-catalyst.

Total Synthesis of Calcaripeptide C

“…Compound 4 was subjected to crucial ring‐closing metathesis in presence of Grubbs‐II [21] catalyst to furnish 18 ( E : Z =86 : 14) that on hydrogenation as well as one pot TBS deprotection furnished alcohol 19 in 77 % yield [22] . Finally oxidation of the alcohol 19 furnished calcaripeptide C, whose spectral data were in good agreement with those reported in the literature [4,5] …”

Copper-catalysed regioselective sulfenylation of indoles with sodium sulfinates

“…When other solvents (e.g. dichloroethane (DCE), DMSO, dioxane and toluene) were used, no products were formed (table 1, entries [19][20][21][22]. When the reaction was performed under N 2 , the result was the same as that under air (entry 23).…”

“…In this regard, the sulfenylation of indoles was the most common method for the synthesis of 3-sulfenylindoles. To date, many sulfenylating agents have been used for the sulfenylation of indoles such as thiols [9][10][11][12][13], disulfides [14][15][16][17][18], sulfonyl chlorides [19][20][21], sulfonyl hydrazides [22][23][24], N-thioimides 2018 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.…”

Chemoenzymatic Hydroxymethylation of Carboxylic Acids by Tandem Stereodivergent Biocatalytic Aldol Reaction and Chemical Decarboxylation

“…Enantiomerically pure 2-substituted 3-hydroxycarboxylate esters are an important class of chiral building blocks widely used in organic synthesis. − For example, ( S )- and ( R )-methyl 3-hydroxy-2-methylpropanoate (i.e., Roche esters) are largely employed as precursors for the preparation of bioactive natural compounds and pharmaceuticals (e.g., discodermolide with potent antimitotic activity, epothilone analogue ZK-Epo (sagopilone), the ionophore antibiotic zincophorin, cytotoxic marine natural products auripyrones A and B, the depsipeptide stevastelin B3, and the antifungal polyketide soraphen A). − Other chiral 2-substituted 3-hydroxycarboxylate esters can be found in the preparation of peptide deformylase inhibitors (Figure ). , …”