Shortly: 1 eq of 4-hydroxybenzaldehyde was suspended in chloroform, 1.05 eq of [Boc.sub.2]O and 0.1 eq of 4-dimethylaminopyridine
General procedure for direct benzoylation: To a solution of the hydroxyl compound in anhydrous pyridine (1 mL) was added benzoyl chloride at 0[degrees]C followed by addition of catalytic amount of 4-dimethylaminopyridine
This claim has been demonstrated in the research of Auzely-Velty and Rinaudo (2003), for the synthesised starch betaine derivatives using disopropylcarbodiimide and 4-dimethylaminopyridine
as coupling agents in an aprotic polar solvent, which carry cleavable cationic groups derived from naturally occurring glycine-betanine.
Monomethoxy poly(ethylene glycol) (MW 2000, mPEG2000), poly(ethylene glycol) (MW 2000, PEG2000), 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCI), and 4-dimethylaminopyridine
(DMAP) were purchased from Sigma-Aldrich (USA).
(Xi'an, China); stannous octoate and caprolactone were purchased by Sigma Corporation; succinic anhydride, tosyl chloride, and polyethylene glycol (4000) were purchased from Tianjin Guangfu Chemical Institute; 4-dimethylaminopyridine
, Nhydroxysuccinimide, and N,N'-dicyclohexyl carbodiimide were purchased from GL Biochem (Shanghai) Ltd.
(DMAP) and dibutyltin dilaurate (DBTDL) were purchased from GE Co., USA.
We have found that addition donor ligands such as 1-methylimidazole or 4-dimethylaminopyridine
(DMAP) are capable of completely inhibiting the metathesis reaction, such as RCM and ROMP, when at least two equivalents are used to completely produce a six-coordinate species of low activity.
However, in recent research described during the talk, which was performed together with fellow graduate student Eric Rivard, MCIC, in Ian Manners, FCIC's, group at the University of Toronto, the presence of a strong donor ligand (L) such as 4-dimethylaminopyridine
has been found to allow the labile cations to be isolated and fully characterized (Scheme 3).
The use of 1-methyladenine or 4-dimethylaminopyridine
as activating groups ([ILLUSTRATION FOR FIGURE 4 OMITTED], line 2) results in the formation of oligomers in which 90% of the phosphodiester bonds are 3[prime],5[prime]-linked (9, 10).
Folate (FA), dicyclohexylcarbodiimide (DCC), N-hydroxysuccinimide (NHS), dioxotetrahydrofuran, and 4-dimethylaminopyridine
(DMAP) were purchased from Aladdin Industrial Co.
The hydroxyl group of (4) was coupled with the ibuprofen derivative (2) in the presence of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and 4-dimethylaminopyridine
(DMAP) in DMF to afford the conjugate (5) in moderate yield.
Acetic anhydride, 4-dimethylaminopyridine
(DMAP), ethanol and n-hexane used were obtained from Fluka.