Vinylogy: Advances in asymmetric catalysis using the bifunctional cinchona alkaloid/thioureas enabled an umpolung of classical Cβ reactivity 3-alkylidene oxindoles, thus allowing development first and sole example a direct, organocatalytic vinylogous Michael (AVM) reaction with nitroolefins. Detailed facts importance to specialist readers are published as "Supporting Information". Such documents peer-reviewed, but not copy-edited or typeset. They made available submitted by authors. Please...

Modulation of the complex reactivity cyclohexenylidene malononitriles using diverse β-aryl-substituted enals and proper organocatalytic modalities resulted in divergent asymmetric reaction patterns to furnish angularly fused or bridged carbabicyclic frameworks. In particular, use remotely enolizable dicyanodienes 1, under one-pot sequential amine/NHC catalysis, led [3 + 2] cycloaddition afford ε,δ-bonded spiro[4.5]decanone structures 5. Alternatively, modifying standard amine catalysis by...

Abstract While several protocols exist for the asymmetric functionalization of pyrazolinones at α‐position relying on nucleophilic addition or annulation procedures, use α‐alkylidene electron‐rich analogues in vinylogous coupling to carbon electrophiles is substantially an uncharted domain. We now report, first time, that alkylidenepyrazolinones carrying enolizable γ‐position efficiently participate direct and asymmetric, catalytic Michael‐type additions nitroolefins providing expected...

Abstract 3‐Alkylidene‐2‐oxindoles represent a simple, yet enabling subfamily of indole alkaloids, and their ability to react as electron‐poor acceptors has largely been investigated. In contrast, utility pronucleophilic synthons remains elusive. this context, the present article describes successful execution direct, organocatalytic asymmetric Michael addition prochiral 3‐alkylideneoxindoles nitroolefins. A variety γ‐substituted alkylideneoxindoles carrying two stereocenters at both γ‐...

Abstract A direct aminocatalytic synthesis has been developed for the chemo‐, regio‐, diastereo‐, and enantioselective construction of densely substituted polycyclic carbaldehydes containing fused cyclohexadiene rings. The chemistry utilizes, first time, remotely enolizable π‐extended allylidenemalononitriles as electron‐rich 1,3‐diene precursors in a eliminative [4+2] cycloaddition with both aromatic aliphatic α,β‐unsaturated aldehydes. generality process is demonstrated by approaching...

Vinylogie: Fortschritte in der asymmetrischen Katalyse mit difunktionellen Chinaalkaloiden/Harnstoffen ermöglichten eine Umpolung klassischen Cβ-Reaktivität von 3-Alkylidenoxindolen. Damit gelang die Entwicklung des ersten und einzigen Beispiels einer direkten, organokatalytischen vinylogen Michael(AVM)-Reaktion Nitroolefinen.

The first uncatalyzed, diastereoselective vinylogous Mukaiyama aldol reaction is reported, between pyrrole/furan-based dienoxy silanes and aromatic aldehydes on salty water/methanol medium, at almost human body temperature, under ultrasonic irradiation. With pyrrole dienes the anti-selective, while that of furan syn-selective. dual role water as both medium promoter highlighted.

Abstract We introduce novel 3‐alkenyl‐2‐silyloxyindole nucleophiles and demonstrate their utility by developing an unprecedented vinylogous Mukaiyama‐type aldol reaction with aromatic aldehydes. This displays excellent levels of γ‐site selectivity diastereoselectivity delivers valuable hydroxylated oxindoles bearing a substituted exocyclic double bond at the C‐3 position. A preliminary trial asymmetric, catalytic version was conducted, it showed promising enantioselectivity for desired products.

Abstract Denmark’s chiral bisphosphoramide/silicon tetrachloride system performs as an excellent Lewis base‐Lewis acid catalyst for the vinylogous Mukaiyama aldol reaction of pyrrole‐ and furan‐based dienoxy silanes with aromatic heteroaromatic aldehydes. This asymmetric methodology provides a powerful synthetic entry to variety δ‐hydroxylated γ‐butenolide‐type frameworks high efficiency valuable margins regio‐, diastereo‐, enantioselectivity. Notably, nature heteroatom within silane donor...

An unprecedented technique for the in situ generation of indolyl ortho-quinodimethanes from 2-methylindole-based methylenemalononitriles by amine-mediated remote C(sp(3) )-H deprotonation was developed. These intermediates were efficiently trapped diverse enals to provide a rapid entry 2,9-dihydro-1H-carbazole-3-carboxyaldehyde structures through formal asymmetric [4+2] eliminative cycloaddition governed α,α-diphenylprolinol trimethylsilyl ether catalyst.

The silyloxy diene-based construction of carbasugars, previously exploited for the synthesis four carbocyclic furanose and pyranose analogues, has been investigated further. By introducing a novel silylative cycloaldolization protocol by adjusting couple minor transformations, efficiency this synthetic sequence was greatly improved. Through series lactone/thiolactone aldehyde cyclization precursors, carbafuranoses (4a-carba-beta-D-xylofuranose, 4a-carba-beta-D-ribofuranose,...

A chiral, divergent synthesis of two carbafuranosylamines, 1 and 2, carbapyranosylamines, 3 4, carbafuranosylamino acids, 5 6, carbapyranosylamino 7 8, has been achieved. Highlights the procedure include following: a diastereoselective crossed vinylogous Mukaiyama aldol coupling between N-(tert-butoxycarbonyl)-2-[(tert-butyldimethylsilyl)oxy]pyrrole (TBSOP, 9) 2,3-O-isopropylidene-D-glyceraldehyde (10) for assembly target compound carbon backbone; high-yielding silylative cycloaldolization...

The feasibility of sequential vinylogous aldol (intermolecular)/silylative (intramolecular) addition reactions involving furan- and pyrrole-based dienoxysilanes, 6 12, in the synthesis carbasugar frameworks is illustrated by preparation scantily investigated carbaseptanose carbaoctanose representatives this class compounds. target compounds, 1, 2, 3, ent-2, ent-3, 4, were obtained from readily available carbohydrate precursors (5 19) yields 21-30% over 8-12 steps. irreversible silylative...

An efficient, stereocontrolled synthesis of (6S,7S,8S,8aR)-6,7,8-trihydroxyindolizidine (alias 1-deoxy-7,8-di-epi-castanospermine) (14) has been developed, which exploits an asymmetric vinylogous Mukaiyama aldol reaction (VMAR) between N-(tert-butoxycarbonyl)-2-(tert-butyldimethylsilyloxy)pyrrole (1) and 2,3-O-isopropylidene-D-glyceraldehyde (2) to construct the initial pyrrolidine building block 3, ene-ene ring closing metathesis (RCM) (9 10) install indolizidine skeleton. The synthetic...

Abstract A direct aminocatalytic synthesis has been developed for the chemo‐, regio‐, diastereo‐, and enantioselective construction of densely substituted polycyclic carbaldehydes containing fused cyclohexadiene rings. The chemistry utilizes, first time, remotely enolizable π‐extended allylidenemalononitriles as electron‐rich 1,3‐diene precursors in a eliminative [4+2] cycloaddition with both aromatic aliphatic α,β‐unsaturated aldehydes. generality process is demonstrated by approaching...

The discovery of chemical methods enabling the construction carbocycle-fused uracils which embody a three-dimensional and functional-group-rich architecture is useful tool in medicinal chemistry oriented synthesis. In this work, an unprecedented amine-catalyzed [4+2] cross-cycloaddition documented; it involves remotely enolizable 6-methyluracil-5-carbaldehydes β-aryl enals, chemoselectively produces two novel bicyclic tricyclic fused uracil chemotypes good yields with maximum level...

The behaviour of the Ce(IV)-catalyzed Belousov-Zhabotinsky (BZ) system has been monitored at 20.0 degrees C in unstirred batch conditions absence and presence different amounts non-ionic micelle-forming surfactants hexaethylene glycol monodecyl ether (C10E6) monotetradecyl (C14E6). influence on both kinetics oxidation malonic acid (MA) by Ce(IV) species BZ reaction stirred also studied over a wide surfactant concentration range. experimental results have shown that, conditions,...

Efficient, total syntheses of novel 2-deoxy-2-amino-5a-carba-β-l-mannopyranuronic acid (1) and 2-deoxy-2-amino-5a-carba-β-l-mannopyranose (2), a positional stereoisomer validamine, have been achieved in 28% 24% overall yields 12 steps 13 steps, respectively, from 2-[(tert-butyldimethylsilyl)oxy]furan (3) (2S)-2,3-O-isopropylideneglyceraldehyde N-benzyl imine (4) via two highly diastereoselective Mukaiyama aldol-related chemical maneuvers. The strategy, which furnishes the targeted...

A short and practical entry to optically pure 5a-carbahexopyranose 1-thio-5a-carbahexopyranose representatives is described. Besides a few functional group protecting manipulations, the synthetic scheme counts on two fundamental carbon−carbon bond-forming reactions, namely (i) regio- stereoselective aldol addition between heterocyclic (silyloxy)diene donors (6 or 13) D-glyceraldehyde as acceptor (7) (ii) chemo- silylative cycloaldolization involving bifunctional aldehydes (10, 16, 21). The...

Abstract The discovery of chemical methods enabling the construction carbocycle‐fused uracils which embody a three‐dimensional and functional‐group‐rich architecture is useful tool in medicinal chemistry oriented synthesis. In this work, an unprecedented amine‐catalyzed [4+2] cross‐cycloaddition documented; it involves remotely enolizable 6‐methyluracil‐5‐carbaldehydes β‐aryl enals, chemoselectively produces two novel bicyclic tricyclic fused uracil chemotypes good yields with maximum level...

Abstract A two‐step, one‐pot sequence under chiral amine—NHC catalysis allows the approach to spiro[4.5]decanone structures in a diastereoselective manner with high e.e.