Search results for "Sequence"

Multicomponent Synthesis of Benzothiophen-2-acetic Esters by a Palladium Iodide Catalyzed S-cyclization – Alkoxycarbonylation Sequence

2021

A catalytic carbonylative approach to the multicomponent synthesis of benzothiophene derivatives from simple building blocks [1-(2-(methylthio)phenyl)prop-2-yn-1-ols, carbon monoxide, and an alcohol)] is presented. It is based on an S-cyclization-demethylation-alkoxycarbonylation-reduction sequence promoted by the PdI2/KI catalytic system, occurring under relatively mild conditions (40 atm, 80 °C, 15 h). Benzothiophene-2-acetic esters are obtained in moderate to good yields (35–70%) starting from variously substituted substrates in combination with different alcohols as external nucleophiles (17 examples). (Figure presented.).

Synthesis of small carboranylsilane dendrons as scaffolds for multiple functionalizations.

2006

Small carbosilane dendrons in which a closo-carborane is located at the focal point have been prepared by a sequence of steps involving hydrosilylation and reduction reactions. These compounds are used as scaffolds for peripheral functionalization with styrene, chlorovinylstyrene, or suitable carboranes, while keeping the C(cluster)-Si (C(c)-Si) bond. Modification of the core by reduction of the carborane with Mg/BrCH2CH2Br was also achieved.

ChemInform Abstract: Cyclocondensation of α-Aminonitriles and Enones: A Short Access to 3,4-Dihydro-2H-pyrrole 2-Carbonitriles and 2,3,5-Trisubstitut…

2010

The reaction of α,β-unsaturated carbonyl compounds with aminoacetonitrile hydrochloride furnishes 3,5-disubstituted 3,4-dihydro-2H-pyrrole-2-carbonitriles in a one-pot reaction sequence. While these products can serve as starting materials for the preparation of polysubstituted pyrrolizidines, they are kinetically stable against the base-induced elimination of HCN. In contrast, their 2-substituted analogues obtained from α-substituted α-aminonitriles can be readily converted to the corresponding 2,3,5-trisubstituted pyrroles under microwave irradiation. The key step presumably involves the thermal electrocyclization of a stabilized 2-azapentadienyl anion formed by condensation of the reacta…

Addition of α-Aminonitriles to α,β-Unsaturated Carbonyl Compounds: A One-Pot Synthesis of Polysubstituted Pyrrolidines.

2003

The vinylogous addition of deprotonated N-alkyl-α-aminonitriles to α,β-unsaturated carbonyl compounds yields cyclic intermediates which can be reduced to form polysubstituted pyrrolidines in a one-pot reaction sequence. Since the cyano substituent is lost in the reduction step, the aminonitriles serve as easily accessible (N-alkylamino)-substituted carbanion equivalents.

ChemInform Abstract: Reactions of Pyrano(3,4-b)indol-3-ones with Dienophiles: Consecutive (4 + 2) Cycloaddition/Cycloreversion/1,2 Elimination.

1990

Methylpyrano[3,4-b]indol-3-ones 1 react with selected dienophiles (as acetylene equivalents) in a consecutive Diels-Alder/cycloreversion/1,2 elimination reaction sequence to furnish the 1-methyl- and 1,4-dimethylcarbazoles 4.

Developments in the Synthesis of Glycopeptides Containing Glycosyl l-Asparagine, l-Serine, and l-Threonine

1994

ChemInform Abstract: Electroorganic Synthesis of Nitriles via a Halogen-Free Domino Oxidation-Reduction Sequence.

2016

A direct electroorganic sequence yielding nitriles from oximes in undivided cells is reported. Despite the fact that intermediate nitrile oxides might be formed, the method is viable to prepare benzonitriles without substituents ortho to the aldoxime moiety. This constant current method is easy to perform for a broad scope of substrates and employs common electrodes, such as graphite and lead.

Convenient Synthesis of 3-Cinnamoyl-2-styrylchromones: Reinvestigation of the Baker-Venkataraman Rearrangement

2010

An efficient and straightforward, one-pot sequence gives access to highly functionalized 3-cinnamoyl-2-styrylchromones in excellent yields. The low solubility of the target molecules allows convenient isolation. The formation of an α,α-dicinnamoylated acetophenone, as a consequence of a two-fold Baker-Venkataraman sequence, has to be anticipated.

ChemInform Abstract: Syntheses of Sialyl Lewis A Glycopeptides - A Partial Sequence of the P-Selectin Ligand PSGL-1.

2000

1,2,4-Oxadiazole rearrangements involving an NNC side-chain sequence.

2009

The thermal rearrangement of N-1,2,4-oxadiazol-3-yl-hydrazones into 1,2,4-triazole derivatives is reported. This represents the first example of a three-atom side-chain rearrangement involving an NNC sequence linked at the C(3) of the oxadiazole. The reactions carried out under solvent-free conditions produced good to high yields of the final products.