- Di-tert-butyl Ethynylimidodicarbonate as a General Synthon for the β-Aminoethylation of Organic Electrophiles: Application to the Formal Synthesis of Pyrrolidinoindoline Alkaloids (±)-CPC-1 and (±)-Alline
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The reagent di-tert-butyl ethynylimidodicarbonate is demonstrated as a β-aminoethyl anion synthetic equivalent. It can be used to install ethyleneamine groups by exploiting its terminal alkyne reactivity with common organic electrophiles. Reactions exemplified with this terminal ynimide reagent include additions to imines, aldehydes, ketones, pyridinium salts, Michael acceptors, epoxides, and Pd-catalyzed Sonogashira couplings. Subsequent regioselective [3 + 2] cycloadditions of the alkynyl-imides (ynimides) generate N,N-di-Boc imide-functionalized triazole and isoxazole heterocycles. Reduction of the ynimides with Pd-catalyzed hydrogenation generates ethyleneimides with easily removable N,N-di-Boc-carbamate protecting groups, allowing for a flexible ynimide-based approach to ethyleneamine installation. The utility of this two-step aminoethylation strategy was demonstrated in the short formal syntheses of pyrrolidinoindoline alkaloids (±)-CPC-1 and (±)-alline. Analogously, the reagent (N,N,N′)-tri-Boc 2-ethynylhydrazine serves as a β-hydrazinoethyl anion synthetic equivalent.
- Beveridge, Ramsay E.,Hu, Yiwei,Gregoire, Bruce,Batey, Robert A.
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p. 8447 - 8461
(2020/07/16)
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- Enantioselective Copper(II)/Box-Catalyzed Synthesis of Chiral β3-Tryptophan Derivatives
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β-Amino acids and their derivatives are important building blocks for the preparation of various bioactive compounds and materials. We developed a highly efficient method for the synthesis of β3-tryptophan derivatives based on enantioselective Friedel-Crafts alkylation of indoles with phthaloyl-protected aminomethylenemalonate in the presence of chiral Cu(OTf)2/iPrBox complex as a catalyst. A wide range of indoles with electron-donating and electron-withdrawing substituents gave the desired products in high yields (up to 99 %) and excellent enantioselectivities (up to 99 % ee). In the case of pyrrole the Friedel-Crafts product was obtained in up to 90 % yield and up to 82 % ee.
- Tarasenko, Elena A.,Shestakov, Ivan V.,Rybakov, Victor B.,Beletskaya, Irina P.
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p. 3913 - 3918
(2019/07/12)
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- Synthesis, Properties and Use of Nitridotricarbonic Acid Tri-tert-Butyl Ester
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Exhaustive tert-butoxycarbonylation of Boc2NH with Boc2O-DMAP furnishes Boc3N in nearly quantitative yield.This stable compound is susceptible to nucleophiles and affords Boc2NH upon aminolysis.The properties of Boc3N have been exploited in a practical one-pot procedure for the synthesis of Boc2NH from NH4Cl, which is particularly economical in the preparation of Boc215NH.
- Degerbeck, Fredrik,Grehn, Leif,Ragnarsson, Ulf
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p. 896 - 898
(2007/10/02)
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- A Convenient One-Flask Preparation of Di-t-butyl Iminodicarbonate: A Versatile Gabriel Reagent
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An improved synthesis of di-t-butyl iminodicarbonate from formamide and di-t-butyl dicarbonate with dimethylaminopyridine as a catalyst followed by aminolytic removal of the formyl group is described as well as a few applications related to the synthesis of primary amines.
- Grehn, Leif,Ragnarsson, Ulf
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p. 275 - 276
(2007/10/02)
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- Synthesis of Analogues of γ-Aminobutyric Acid. Part 11. Unsaturated and Saturated Tetronic Acid Derivatives
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5-(2-Aminoethylidene)-4-hydroxyfuran-2(5H)-one (3) and the corresponding reduced 5-(2-aminoethyl) derivative (4) have been synthesised as conformationally restricted analogues of the neurotransmitter GABA.The use of the t-butyl protected reagents bis(t-butoxycarbonyl)amine and 5-ethylidene-4-t-butoxyfuran-2(5H)-one (7b) allowed generation of the required amino compounds under mild acidic deprotection conditions in the final step.
- Allan, Robin D.,Johnston, Graham A. R.,Kazlauskas, Rymantas,Tran, Hue W.
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p. 2983 - 2986
(2007/10/02)
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- Carbonyl Isocyanate Isothiocyanate
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A synthesis of carbonyl isocyanate isothiocyanate (1) is described. 1 reacts with H2O, H2S, or HCl to give the thiadiazines 3, 6, and 14, resp.With one mol equivalent of alcohol the isothiocyanates 7 are obtained which form with further alcohol or amines compounds 8 - 10.With one mol equivalent of amine 1 gives the carbamoyl isothiocyanates 11 which form compounds 12 and 13 with further amine.Compound 1 can be chlorinated to carbonyl isocyanate isocyanide dichloride (18).Partial hydrolysis of 18 leads to carbamoyl isocyanide dichloride (19) yielding with aliphaticamines the stable carbamoyl carbodiimides 16.With alcohols 18 reacts to give the (dichloromethylene)allophanic esters 20.
- Bunnenberg, Rolf,Jochims, Johannes C.
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p. 2064 - 2074
(2007/10/02)
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