Rapid ynthesis and Purification of ulfahydantion Library Using Microwave Assisted rganic ynthesis and Automated Flash Chromatography hahnaz Ghassemi, Ph.D. March 17, 2005 Discovery Chemistry Group 1725 Discovery Drive Charlottesville, VA 22911
Background ulfahydantoin compounds are noted for their broad biological activity R 1 HI 2 R Pk a comparable to carboxylic acid ~ 4 Most syntheses rely on long reaction time and tedious work-up process These conditions are not convenient for fast drug discovery 2
3 This talk will overview the recent advances in technologies which has enabled the chemist to design efficient strategies to shorten reaction time and increase product purity
Recent Advances for Rapid ynthesis and Purification Microwave Assisted rganic ynthesis (MA) Automated Flash purification horten Compound production time Increase product purity Reproducible results 4
The First MA of alkaloid Lepidiline B R 1 R 2 H 4 AC + Microwave H 180 C, 5 min. R 1 R 2 H PhCH 2 Cl Microwave 180 C, 5 min. 43% over 2 steps Total reaction time: 10 min R 1 R 2 + Alkaloid lepidiline B Wolkenberg,.E.; Wisnoski, D.W.; Lindsley, C.W.; Zhao, Z.; Leister, W.; Wang, Y. rg. Lett. 2004, 6, 1453 5
olid upported Reagents in Controlled MA olid supported reagents are an important tool in solution phase chemistry Eliminates reaction work-up Real time monitoring R H + R 1 H R 2 DCM R R 1 R 2 Temp Conventional* R.T Microwave 150 ºC Time 12-24 hr. 5 min. olid-dcc 3 eq. 1 eq. illicycle.com/html/english/products Argotech.com/products/lead/resins/index.htm 6
MA + olid upported Reagent AMIDE CUPLIG A general and rapid method for the preparation of amides using bonded-carbodiimide + microwave heating H Ps- Carbodiimide amine, HBT MP Microwave 5 min. H H auer,d., Kalvin, D., Phelan, K., rg. Lett. 2003, 5, 4721 7
ulfahydantion General scheme for sulfahydantion 1. Reductive alkylation 2. ulfamide synthesis 3. Cyclitive cleavage R 1 HI 2 R Total time: 4 Days 8
ulfahydantion Literature procedure H 2 HCl 4-MeC 6 H 4 CH aac, acbh 3 H Me vernight reaction, followed by many steps of extractions H 2 2 Cl,Et 3 Two days reaction, followed by extractions and chromatography H 2 2 Me ame,meh Me H 2 ne day reaction, followed by neutralization and extractions 9
Modifications in ulfahydantion ynthesis Procedure Microwave irradiation used to shorten reaction time olid supported CBH used to eliminate liquid-liquid extraction and reduce reaction workup Automated flash chromatography used for fast isolation of product 10
11 Instrumentation for MA
Microwave-Assisted Reductive Amination MA in one-pot two step reductive alkylation H 2 H DIEA, MeH + Microwave 2 min. Me 90 ºC Microwave 3 min. 80 ºC Me -CBH 3 Imine H Amine Me Total time for synthesis: 5 min 12
Microwave-Assisted Reductive Amination Racemization study + The extent of racemization in the two step one pot microwave-assisted reductive amination was studied by comparing 1 H-MR (500 MHz) of the LL and DL diastereomers Et Et H H H Boc H Boc LL DL o racemization was detected 13
14 1 H-MR of DL diastereomer
Microwave-Assisted Amine ynthesis Method A: 2 eq. 1 M acbh 4 Method B: 2 eq. i-cbh 4 Method C: 2 eq. P-CBH 4 H Me H Br H CF 3 Cl H Cl Method A 79% 83% 84% 68% Method B 74% 79% 85% 63% Method B 72% 80% 73% 59% H H H Cl Cl H CF 3 H H Method A 85% 89% 88% 88% 75% Method B 79% 84% 80% 78% 73% Method B 80% 80% 77% 81% 65% 15
Microwave-Assisted ulfamides ynthesis Cl C H Microwave + 1 min. 90 ºC H Cl H 2 Helium H Me Et 3, DCM Microwave 4 min. 80 ºC H 2 2 Me Total time for synthesis: 5 min 16
Isolated yield of ulfamides H 2 Br H 2 CF 3 67% 76% H 2 Cl Cl H 2 Et H 2 74% 70% 79% H Boc Et H 2 Et H 2 Et H 2 68% Cl Cl 65% 79% H Boc Product verified by 1 H-MR and M 17
Microwave-Assisted Cyclitive Cleavage ame / MeH H Microwave 2 H 2 2 Me 5 min / 100 ºC Me Total time for synthesis: 5 min 18
ulfahydantion Compounds Isolated yields Cl Cl H 74% H 67% Br H 70% Cl Cl 65% H H 68% H 87% CF 3 H 79% H H H 79% H H 19
ptimized ynthesis of Cyclic ulfamide Conventional method of synthesis 4 days Microwave-assisted organic synthesis 1 hour 20
Microwave-promoted synthesis horter reaction times Minutes instead of hours Rapid testing of creative ideas Expanded reaction diversity ew avenues for chemistry Possible to run more difficult reactions due to higher temperatures Reproducible results Temperature and pressure controlled Growing interest in microwave synthesis Many papers and reviews coming out in 2000-2005 21
ptimized Purification cheme Advancement in rapid isolation of product using ormal phase and Reverse phase Automated Flash chromatography 22
Conventional Workup & Purification f Reductive Amination Product 1. olvent is evaporated 2. The residue is suspended in 5% aq ah and extracted with EtAc (x2) 3. rganic extract is dried over Mg 4 4. Concentrated under reduced pressure 5. Crude product is taken up in EtAc and extracted with 5% HCl (x 2) 6. The combined aqueous extracts is neutralized with solid K 2 C 3 7. Cooled to <5 ºC in an ice bath, and treated with 50% aq ah 8. The aqueous layer was extracted with EtAc (x 3) 9. The EtAc extracts is combined, dried over Mg 4 and concentrated 23
Flash Workup & Purification Using olid Bonded Reagent 1. Evaporate solvent in vial using 2 flow 2. Transfer resulting solid onto cartridge Dry-Loading Compression Head 3. Insert Frit on top of sample inside cartridge 4. Load cartridge into barrel & seal using Dry-Loading Compression Head Reaction Mixture 5. Run Automated Flash chromatography 24
Flash Purification of Amine H 2 + H H H BC DIEA, MeH Microwave 2 min. 90 ºC -CBH 3 Microwave 3 min. 80 ºC H H BC Flash isolation TLC of reaction mixture TLC of collected product after Flash Total time for purification: 15 min. 25
Flash Purification of ulfamide H + Me Et Cl H 3, DCM 2 Microwave 4min. 80 ºC H 2 2 Me Product Product TLC of reaction mixture Flash purification Total time for purification: 15 min 26
Conventional Workup & Purification f Cyclitive Cleavage 1. olvent evaporated under reduced pressure 2. Residue taken up in water and washed with ether Me 2 H 3. Aqueous layer acidified to ph <1 with conc HCl 4. Extraction with ethyl acetate (X 2) 5. Dry combined ethyl acetate extracts over Mg 4 6. olvent concentrated under reduced pressure 27
Flash Workup & Purification olution Phase rganic ynthesis 1. Reaction mixture transferred onto amplet 2. amplet inserted onto Flash+ cartridge 3. Load cartridge into barrel and seal using Dry-Loading Compression Head C18 Cartr idge C18 amplet 4. Run Automated Flash chromatography P Automated Purification ystem 28 2
C-18 Flash Purification of Cyclic ulfamide H 2 CF 3 ame / MeH Microwave 5 min. 100 ºC H CF 3 Yield 87% 100% MeH 10% MeH Total time for purification: 15 min 29
1 H-MR of Cyclic ulfamide 1 H-MR of cyclized product after Flash Purification 30
ummary A general procedure for rapid preparation of sulfahydantions using Controlled microwave-heating and Automated Flash purification The products were formed in high yield and purity This procedure was demonstrated to be compatible with benzylic and aromatic aldehydes MA is easily integrated with olid Bonded Reagents Less bonded reagent and shorter time required under microwave heating condition implifies workflow and enhances the rate of drug discovery 31
Acknowledgements Dr. Pino Pilotti (Uppsala, E) Dr. John Gupton (University of Richmond, VA) 32