title: Propargylation of arabinogalactan with propargyl halides--a facile route to new functionalized biopolymers.
abstract: New arabinogalactan propargyl ethers with degree of substitution (DS) up to 2.8 have been obtained by propargylation of arabino-3,6-galactan (AG) with propargyl bromide (PB) in the two-phase system 30-60% КОН aqueous solution/toluene in the presence of triethylbenzylammonium chloride (TEBAС) or without catalyst (ambient temperature, 1-24 h) in 20-87% yields. The highest yields have been reached using TEBAС as phase-transfer catalyst, though the non-catalytic version proves to be also efficient (DS 2.8, 70% yield). The propargylation of AG is less effective in the systems MОН (M=Na, K)/DMSO. DS of propargyl AG reaches 1.8 (70% yield) when propargyl chloride is used as propargylating agent, while with PB under the same conditions DS value does not exceed 0.4-0.6, the yields being 44-65%. Under the action of t-BuOK/DMSO system, the AG propargyl ethers have been isomerized to the corresponding unstable allenyl ethers. AG propargyl ethers with DS 2.0 have been almost exhaustively metallated with Ag2O/NH3 system to give AG-Ag acetylides derivatives with Ag/C≡C ratio equaling 0.95.
authors.affiliation: A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, 1 Favorsky Str., 664033 Irkutsk, Russia.
authors.forename: Lyudmila A
authors.initials: LA
authors.lastname: Grischenko
authors.forename: Lidiya N
authors.initials: LN
authors.lastname: Parshina
authors.forename: Lyudmila V
authors.initials: LV
authors.lastname: Kanitskaya
authors.forename: Lyudmila I
authors.initials: LI
authors.lastname: Larina
authors.forename: Lyubov N
authors.initials: LN
authors.lastname: Novikova
authors.forename: Boris A
authors.initials: BA
authors.lastname: Trofimov
mesh_terms: D000480:Alkynes / Q000138:chemical synthesis* / Q000737:chemistry*; D001704:Biopolymers / Q000737:chemistry*; D002236:Carbohydrate Conformation; D004987:Ethers / Q000138:chemical synthesis* / Q000737:chemistry*; D005685:Galactans / Q000138:chemical synthesis* / Q000737:chemistry*; D010293:Pargyline / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D000480:Alkynes; D001704:Biopolymers; D004987:Ethers; D005685:Galactans; C531209:propargyl ether; D010293:Pargyline; C458239:propargyl bromide; C005653:arabinogalactan