Synthesis of Dihydrooxepino[3,2-c]Pyrazoles via Claisen Rearrangement and Ring-Closing Metathesis from 4-Allyloxy-1H-pyrazoles
Synthesis of novel pyrazole-fused heterocycles, i.e., dihydro-1H- or 2H-oxepino[3,2-c]pyrazoles (6 or 7) from 4-allyloxy-1H-pyrazoles (1) via combination of Claisen rearrangement and ring-closing metathesis (RCM) has been achieved. A suitable catalyst for the RCM of 5-allyl-4-allyloxy-1H-pyrazoles (...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2018-03-01
|
| Series: | Molecules |
| Subjects: | |
| Online Access: | http://www.mdpi.com/1420-3049/23/3/592 |
| _version_ | 1811241704277147648 |
|---|---|
| author | Yoshihide Usami Aoi Kohno Hiroki Yoneyama Shinya Harusawa |
| author_facet | Yoshihide Usami Aoi Kohno Hiroki Yoneyama Shinya Harusawa |
| author_sort | Yoshihide Usami |
| collection | DOAJ |
| description | Synthesis of novel pyrazole-fused heterocycles, i.e., dihydro-1H- or 2H-oxepino[3,2-c]pyrazoles (6 or 7) from 4-allyloxy-1H-pyrazoles (1) via combination of Claisen rearrangement and ring-closing metathesis (RCM) has been achieved. A suitable catalyst for the RCM of 5-allyl-4-allyloxy-1H-pyrazoles (4) was proved to be the Grubbs second generation catalyst (Grubbs2nd) to give the predicted RCM product at room temperature in three hours. The same reactions of the regioisomer, 3-allyl-4-allyloxy-1H-pyrazoles (5), also proceeded to give the corresponding RCM products. On the other hand, microwave aided RCM at 140 °C on both of 4 and 5 afforded mixtures of isomeric products with double bond rearrangement from normal RCM products in spite of remarkable reduction of the reaction time to 10 min. |
| first_indexed | 2024-04-12T13:40:27Z |
| format | Article |
| id | doaj.art-7452551b25b64e359b639a2a9df51ac0 |
| institution | Directory Open Access Journal |
| issn | 1420-3049 |
| language | English |
| last_indexed | 2024-04-12T13:40:27Z |
| publishDate | 2018-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Molecules |
| spelling | doaj.art-7452551b25b64e359b639a2a9df51ac02022-12-22T03:30:52ZengMDPI AGMolecules1420-30492018-03-0123359210.3390/molecules23030592molecules23030592Synthesis of Dihydrooxepino[3,2-c]Pyrazoles via Claisen Rearrangement and Ring-Closing Metathesis from 4-Allyloxy-1H-pyrazolesYoshihide Usami0Aoi Kohno1Hiroki Yoneyama2Shinya Harusawa3Laboratory of Pharmaceutical Organic Chemistry, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, JapanLaboratory of Pharmaceutical Organic Chemistry, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, JapanLaboratory of Pharmaceutical Organic Chemistry, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, JapanLaboratory of Pharmaceutical Organic Chemistry, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, JapanSynthesis of novel pyrazole-fused heterocycles, i.e., dihydro-1H- or 2H-oxepino[3,2-c]pyrazoles (6 or 7) from 4-allyloxy-1H-pyrazoles (1) via combination of Claisen rearrangement and ring-closing metathesis (RCM) has been achieved. A suitable catalyst for the RCM of 5-allyl-4-allyloxy-1H-pyrazoles (4) was proved to be the Grubbs second generation catalyst (Grubbs2nd) to give the predicted RCM product at room temperature in three hours. The same reactions of the regioisomer, 3-allyl-4-allyloxy-1H-pyrazoles (5), also proceeded to give the corresponding RCM products. On the other hand, microwave aided RCM at 140 °C on both of 4 and 5 afforded mixtures of isomeric products with double bond rearrangement from normal RCM products in spite of remarkable reduction of the reaction time to 10 min.http://www.mdpi.com/1420-3049/23/3/592dihydrooxepino[3,2-c]pyrazolesynthesis4-allyloxy-1H-pyrazolesRCMClaisen rearrangement |
| spellingShingle | Yoshihide Usami Aoi Kohno Hiroki Yoneyama Shinya Harusawa Synthesis of Dihydrooxepino[3,2-c]Pyrazoles via Claisen Rearrangement and Ring-Closing Metathesis from 4-Allyloxy-1H-pyrazoles Molecules dihydrooxepino[3,2-c]pyrazole synthesis 4-allyloxy-1H-pyrazoles RCM Claisen rearrangement |
| title | Synthesis of Dihydrooxepino[3,2-c]Pyrazoles via Claisen Rearrangement and Ring-Closing Metathesis from 4-Allyloxy-1H-pyrazoles |
| title_full | Synthesis of Dihydrooxepino[3,2-c]Pyrazoles via Claisen Rearrangement and Ring-Closing Metathesis from 4-Allyloxy-1H-pyrazoles |
| title_fullStr | Synthesis of Dihydrooxepino[3,2-c]Pyrazoles via Claisen Rearrangement and Ring-Closing Metathesis from 4-Allyloxy-1H-pyrazoles |
| title_full_unstemmed | Synthesis of Dihydrooxepino[3,2-c]Pyrazoles via Claisen Rearrangement and Ring-Closing Metathesis from 4-Allyloxy-1H-pyrazoles |
| title_short | Synthesis of Dihydrooxepino[3,2-c]Pyrazoles via Claisen Rearrangement and Ring-Closing Metathesis from 4-Allyloxy-1H-pyrazoles |
| title_sort | synthesis of dihydrooxepino 3 2 c pyrazoles via claisen rearrangement and ring closing metathesis from 4 allyloxy 1h pyrazoles |
| topic | dihydrooxepino[3,2-c]pyrazole synthesis 4-allyloxy-1H-pyrazoles RCM Claisen rearrangement |
| url | http://www.mdpi.com/1420-3049/23/3/592 |
| work_keys_str_mv | AT yoshihideusami synthesisofdihydrooxepino32cpyrazolesviaclaisenrearrangementandringclosingmetathesisfrom4allyloxy1hpyrazoles AT aoikohno synthesisofdihydrooxepino32cpyrazolesviaclaisenrearrangementandringclosingmetathesisfrom4allyloxy1hpyrazoles AT hirokiyoneyama synthesisofdihydrooxepino32cpyrazolesviaclaisenrearrangementandringclosingmetathesisfrom4allyloxy1hpyrazoles AT shinyaharusawa synthesisofdihydrooxepino32cpyrazolesviaclaisenrearrangementandringclosingmetathesisfrom4allyloxy1hpyrazoles |