scholarly journals Synthesis of fluorinated δ-lactams via cycloisomerization of gem-difluoropropargyl amides

2010 ◽  
Vol 6 ◽  
Author(s):  
Satoru Arimitsu ◽  
Gerald B Hammond
Keyword(s):  
Building Blocks ◽  
Alder Reaction ◽  
Diels Alder ◽  
Tandem Reaction ◽  
Enyne Metathesis ◽  
Metathesis Reaction ◽  
Ring Closing Metathesis ◽  
Diels Alder Reaction

gem-Difluoro-1,7-enyne amides are suitable building blocks for the synthesis of difluorodihydropyridinones via a ring-closing metathesis reaction, and of 4,4-difluoro-3-oxoisoquinolines through a ring-closing metathesis–enyne metathesis tandem reaction. These products, in turn, undergo a Diels–Alder reaction to yield heterotricyclic systems in moderate to good yields.

scholarly journals Ring-closing metathesis of prochiral oxaenediynes to racemic 4-alkenyl-2-alkynyl-3,6-dihydro-2H-pyrans

2020 ◽  
Vol 16 ◽  
pp. 2757-2768
Author(s):  
Viola Kolaříková ◽  
Markéta Rybáčková ◽  
Martin Svoboda ◽  
Jaroslav Kvíčala
Keyword(s):  
Triple Bond ◽  
Building Blocks ◽  
Ester Group ◽  
Alder Reaction ◽  
Diels Alder ◽  
Side Reactions ◽  
Enyne Metathesis ◽  
Ring Closing Metathesis ◽  
2Nd Generation ◽  
Diels Alder Reaction

The prochiral 4-(allyloxy)hepta-1,6-diynes, optionally modified in the positions 1 and 7 with an alkyl or ester group, undergo a chemoselective ring-closing enyne metathesis yielding racemic 4-alkenyl-2-alkynyl-3,6-dihydro-2H-pyrans. Among the catalysts tested, Grubbs 1st generation precatalyst in the presence of ethene (Mori conditions) gave superior results compared to the more stable Grubbs or Hoveyda–Grubbs 2nd generation precatalysts. This is probably caused by a suppression of the subsequent side-reactions of the enyne metathesis product with ethene. On the other hand, the 2nd generation precatalysts gave better yields in the absence of ethene. The metathesis products, containing both a triple bond and a conjugated system, can be successfully orthogonally modified. For example, the metathesis product of 5-(allyloxy)nona-2,7-diyne reacted chemo- and stereoselectively in a Diels–Alder reaction with N-phenylmaleimide affording the tricyclic products as a mixture of two separable diastereoisomers, the configuration of which was estimated by DFT computations. The reported enediyne metathesis paves the way to the enantioselective enyne metathesis yielding chiral building blocks for compounds with potential biological activity, e.g., norsalvinorin or cacospongionolide B.

scholarly journals Ring closing metathesis of prochiral oxaenediynes to racemic 4-alkenyl-2-alkynyl-3,6-dihydro-2H-pyrans

2020 ◽  
Author(s):  
Viola Kolaříková ◽  
Markéta Rybáčková ◽  
Martin Svoboda ◽  
Jaroslav Kvíčala
Keyword(s):  
Triple Bond ◽  
Building Blocks ◽  
Ester Group ◽  
Alder Reaction ◽  
Diels Alder ◽  
The Other ◽  
Side Reactions ◽  
Enyne Metathesis ◽  
Ring Closing Metathesis ◽  
Diels Alder Reaction

Prochiral 4-(allyloxy)hepta-1,6-diynes, optionally modified in the positions 1 and 7 with an alkyl or ester group, undergo chemoselective ring closing enyne metathesis yielding racemic 4-alkenyl-2-alkynyl-3,6-dihydro-2H-pyrans. Among the catalysts tested, Grubbs 1st generation precatalyst in the presence of ethene (Mori conditions) gave superior results compared to more stable Grubbs or Hoveyda-Grubbs 2nd generation precatalysts. This is probably caused by suppression of subsequent side-reactions of the enyne metathesis product with ethene. On the other hand, 2nd generation precatalysts gave better yields in the absence of ethene. The metathesis products, containing both triple bond and conjugated system, can be successfully orthogonally modified. For example, metathesis product of 5-(allyloxy)nona-2,7-diyne reacted chemo- and stereoselectively by Diels-Alder reaction with N-phenylmaleimide affording tricyclic products as the mixture of two separable diastereoisomers, the configuration of which was estimated by DFT computations. The reported enediyne metathesis paves the way to enantioselective enyne metathesis yielding chiral building blocks for compounds with potential biological activity, e.g. norsalvinorin or cacospongionolide B.

Ring-Closing Metathesis Approach to Cage Propellanes Containing Oxepane and Tetrahydrofuran Hybrid System

Synthesis ◽  
2017 ◽  
Vol 49 (24) ◽  
pp. 5339-5350 ◽  
Author(s):  
Sambasivarao Kotha ◽  
Subba Cheekatla ◽  
Darshan Mhatre
Keyword(s):  
Claisen Rearrangement ◽  
Alder Reaction ◽  
Diels Alder ◽  
Ring Closing Metathesis ◽  
Cage Compounds ◽  
Transannular Cyclization ◽  
Diels Alder Reaction ◽  
Grignard Addition ◽  
Key Steps ◽  
First Time

The preparation of a variety of structurally interesting oxygenated cage compounds involving atom-economic processes such as Claisen rearrangement, Diels–Alder reaction, [2+2] photocycloaddition, and ring-closing metathesis (RCM) as key steps is reported. For the first time, oxepane ring system is introduced in cage framework using olefin metathesis as a key step. These cage systems assembled here are difficult to prepare by traditional methods. The synthetic sequence described here opens up new routes to higher order polycycles containing heteroatoms without the involvement of protecting groups. Transannular cyclization observed during Grignard addition and the RCM protocol used here may be applicable to generate unknown oxygenated cage systems.

ChemInform Abstract: Tandem Cross Enyne Metathesis (CEYM)-Intramolecular Diels-Alder Reaction (IMDAR). An Easy Entry to Linear Bicyclic Scaffolds.

ChemInform ◽  
2015 ◽  
Vol 46 (47) ◽  
pp. no-no
Author(s):  
Javier Miro ◽  
Maria Sanchez-Rosello ◽  
Alvaro Sanz ◽  
Fernando Rabasa ◽  
Carlos del Pozo ◽  
...  
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Enyne Metathesis ◽  
Diels Alder Reaction
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