Experimental data for the synthesis of a new dimeric prodelphinidin gallate

This data article contains raw and processed data related to research published in Teixeira et al. (2016) [1]. Here we introduce data acquired from the synthesis of a prodelphinidin dimer gallate. All synthesis steps are described and a dataset for the removal of the protecting on prodelphinidin synthesis is presented. With hydrogenolysis in situ with triethylsilane the hydrogen required is produced and used at the same time, making the reaction possible without resorting to bottled hydrogen. Full NMR and HPLC-ESI-MS analysis data is also provided.


a b s t r a c t
This data article contains raw and processed data related to research published in Teixeira et al. (2016) [1]. Here we introduce data acquired from the synthesis of a prodelphinidin dimer gallate. All synthesis steps are described and a dataset for the removal of the protecting on prodelphinidin synthesis is presented. With hydrogenolysis in situ with triethylsilane the hydrogen required is produced and used at the same time, making the reaction possible without resorting to bottled hydrogen. Full NMR and HPLC-ESI-MS analysis data is also provided.
& 2016 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Value of the data
The data for a simple method for prodelphinidin gallate synthesis with hydrogenolysis in situ is presented; Full NMR analysis data is included for easy identification of the intermediate and final compounds; This synthesis strategy may be applied to other proanthocyanidins.

Benzylation of monomeric flavan-3-ols
To a stirred solution of (-)-EGC 1 and (-)-EGCG 2 in dry DMF, under argon, was added potassium carbonate (K 2 CO 3 ) (10 eq for 1; 17.6 eq for 2) and BnBr (7.7 eq for 1; 13.6 eq for 2). The solution was stirred at 0°C for 2 h and left at room temperature for 72 h for 1 and 24 h for 2. The mixture was extracted with ethyl acetate and water, dried over Na 2 SO 4 , filtered and concentrated. The crude product was purified with silica gel column chromatography (dichloromethane (CH 2 Cl 2 ) for 3 and hexane/ EtOAc 2:1 for 4).

Condensation
EGC5Bn(Bn) 5 and EGCG8Bn 4 (4 eq) were dissolved in CH 2 Cl 2 and trimethylsilyl trifluoromethanesulfonate (TMSOT f ) (0.5 M solution in CH 2 Cl 2 , 1.5 eq) was added dropwise at À 78°C. Therefore the proper time of reaction was tested by following each reaction by TLC. At first the solutions were left to react for 5 min, following the method described by Krohn et al. [2]. However, after that period of time and after checking the reaction products by TLC, it was observed that the upper unit (and limiting reagent) EGC5Bn(Bn) was still present in good quantity. Thereby, the solution was left stirring for 90 min (reaching À 22°C), and left to reach 0°C for 3 h 30 min. The reactions were then quenched by addition of saturated aqueous sodium bicarbonate (Na 2 HCO 3 ) (1 mL). The mixture was extracted with chloroform and the organic phase was washed with water and brine, dried over Na 2 SO 4 , filtered and concentrated. The crude product was purified with silica gel column chromatography with CH 2 Cl 2 as eluent to afford EGC-EGCG13Bn 6.

Hydrogenolysis in situ
To a stirred solution of EGC-EGCG13Bn 25 under argon and Pd/C 10% in MeOH (2-3 mL) was added neat triethylsilane (TES) (10 mmol for each removing group) [3]. A few drops of THF were added to dissolve the reagents. When the reaction was complete (TLC), each mixture was filtered through a 0.20 μm PET Chromafil s syringe filter and the solvent was evaporated under vacuum.