Microwaves in Intramolecular 1,3-Dipolar Cycloaddition

D 2003

Microwaves in Intramolecular 1,3-Dipolar Cycloaddition

POTÁČEK, Milan a Jiří POSPÍŠIL

Základní údaje

Originální název

Microwaves in Intramolecular 1,3-Dipolar Cycloaddition

Autoři

POTÁČEK, Milan a Jiří POSPÍŠIL

Vydání

Gainesville, Speaker's presentation & materials, s. 6-12, 2003

Nakladatel

CEM

Další údaje

Jazyk

angličtina

Typ výsledku

Stať ve sborníku

Obor

10401 Organic chemistry

Stát vydavatele

Spojené státy

Utajení

není předmětem státního či obchodního tajemství

Organizační jednotka

Přírodovědecká fakulta

Klíčová slova anglicky

1;3-dipolar cycloaddition; microwave-initiated; intramolecular reaction

Štítky

1, 3-dipolar cycloaddition, intramolecular reaction, microwave-initiated

Změněno: 10. 9. 2004 16:42, prof. RNDr. Milan Potáček, CSc.

Anotace

V originále

In our paper we would like to inform about our results with application microwave initiated process under solvent-free conditions. The reaction was carried out as one pot process when the 1,3-dipole was generated in situ by the reaction of o-allyloxybenzaldehyde 1 (sometimes ç{-substituted with substituents R1, R2) with a secondary amine 2 containing electron-withdrawing group. Influence of the substitution at the side chain double bond as well as the substitution at the nitrogen atom and electron-withdrawing groups at amine upon the yield and stereochemistry of products were searched. Reactions were carried out at both the classical heating and under microwave initiation. As the best conditions found for the microwave initiated reactions was temperature 2000C and the reaction time 15 min. At lower temperature the conversion was not full, at higher temperature a decomposition of intermediates as well as products occurred. It has been proved rather high sensitivity of the chemical reaction on the bulkiness of substituents bound at nitrogen atom of amine. The bulky substituents like terc-butyl, 1-adamantyl did not react, the reaction with isopropyl group was retarded. This observation corresponds to sterical demands of the molecule of 1,3-dipole when enters into reaction with intramoleculary bound dipolarophile. The reactions with unsubstituted allyloxy group proceed with excellent stereoselectivity when only one stereoisomer is formed. The same stereoselectivity was observed when dipolarophiles in cis-configuration at double bond bound in side chain of aromatic ring playing dipolarophile role were used (only one steroisomer was formed). When the configuration on double bond was trans two stereoisomers were isolated in different ratio depending on the nitrogen substitution R3. Nevertheless, the generated ylide always in the reaction possessed anti conformation. We suppose the transition state and its sterical demands influence the stereochemistry of the product formed.

Návaznosti

OC D10.20, projekt VaV

Název: Mikrovlnami aktivované chemické přeměny

Investor: Ministerstvo školství, mládeže a tělovýchovy ČR, Mikrovlnami aktivované chemické přeměny

Citovat

POTÁČEK, Milan a Jiří POSPÍŠIL. Microwaves in Intramolecular 1,3-Dipolar Cycloaddition. In Speaker's presentation & materials. Gainesville: CEM, 2003, s. 6-12.

@inproceedings{557659,
   author = {Potáček, Milan and Pospíšil, Jiří},
   address = {Gainesville},
   booktitle = {Speaker's presentation & materials},
   keywords = {1;3-dipolar cycloaddition; microwave-initiated; intramolecular reaction},
   language = {eng},
   location = {Gainesville},
   pages = {6-12},
   publisher = {CEM},
   title = {Microwaves in Intramolecular 1,3-Dipolar Cycloaddition},
   year = {2003}
}

TY  - CONF
ID  - 557659
AU  - Potáček, Milan - Pospíšil, Jiří
PY  - 2003
TI  - Microwaves in Intramolecular 1,3-Dipolar Cycloaddition
PB  - CEM
CY  - Gainesville
KW  - 1;3-dipolar cycloaddition
KW  - microwave-initiated
KW  - intramolecular reaction
N2  - In our paper we would like to inform about our results with application microwave initiated process under solvent-free conditions. The reaction was carried out as one pot process when the 1,3-dipole was generated in situ by the reaction of o-allyloxybenzaldehyde 1 (sometimes ç{-substituted with substituents R1, R2) with a secondary amine 2 containing electron-withdrawing group. Influence of the substitution at the side chain double bond as well as the substitution at the nitrogen atom and electron-withdrawing groups at amine upon the yield and stereochemistry of products were searched. Reactions were carried out at both the classical heating and under microwave initiation. As the best conditions found for the microwave initiated reactions was temperature 2000C and the reaction time 15 min. At lower temperature the conversion was not full, at higher temperature a decomposition of intermediates as well as products occurred. It has been proved rather high sensitivity of the chemical reaction on the bulkiness of substituents bound at nitrogen atom of amine. The bulky substituents like terc-butyl, 1-adamantyl did not react, the reaction with isopropyl group was retarded. This observation corresponds to sterical demands of the molecule of 1,3-dipole when enters into reaction with intramoleculary bound dipolarophile. The reactions with unsubstituted allyloxy group proceed with excellent stereoselectivity when only one stereoisomer is formed. The same stereoselectivity was observed when dipolarophiles in cis-configuration at double bond bound in side chain of aromatic ring playing dipolarophile role were used (only one steroisomer was formed). When the configuration on double bond was trans two stereoisomers were isolated in different ratio depending on the nitrogen substitution R3. Nevertheless, the generated ylide always in the reaction possessed anti conformation. We suppose the transition state and its sterical demands influence the stereochemistry of the product formed.
ER  -

POTÁČEK, Milan a Jiří POSPÍŠIL. Microwaves in Intramolecular 1,3-Dipolar Cycloaddition. In \textit{Speaker's presentation \&{} materials}. Gainesville: CEM, 2003, s.~6-12.

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