الفهرس 
Quinazoline nucleosidesOnly 14 pages are availabe for public view
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Abstract
Quinazoline -2,4( 1H,3H )-diones 8 were silylated with 1,1,1,3,3,3- hexamethyldisilazane ( HMDS ) in the presence of ammonium sulphate and condensed with methyl 3-azido--5-O-tert-butydliphenylsilyl-2,3-dideoxy-Derythro- penyohanoside 339, which was prepared fiom 2-deoxy-D-ribose 332 by consecutive methyl glycosidation, 5-OH protection with tertbutylchlorodiphenylsilane, replacement of 3-OH with iodine which in turn replaced by azido goup using , trirnethylsilyl trifluoromethanesulfonate ( TMS triflate ) as the catalyst to afford 1 -( 3-azido-5-0-tert-b~tyldiphenylsil~l-2,3- dideoxy- a, f3 -D-erythro-pentofuranosyl ) quinazoline-2,4( 1 H,3H )-diones 340 whlch on treatment with tetrabutylammonium fluoride in THF gave 1-(3-azido-’ 2,3-dideoxy- a -D-elythro-pentobanosyl) quinazoline-2,4(1 H,3H)-diones 341 and their conesponding P -anomers 3 . Theno [2,3-d]pyrirmd~ne-2,4(1 H,3H)-dione 56 was silylated with HMDS and condensed with 339 in acetonitrile in the presence of TMS triflate to yield 1 -(3-azido-5-O-tert-butyldiphenylsilyl-2,3-dideoxy- a, P -D-erythro - pentofixanosyl) thieno [2,3-dlpyrimidine-2,4(1 H,3N)-dione 342. Deprotection of - 342 was achieved by treatment with Bu,NF / THF to produce 1-( 3-azido- 2,3-ddeoxy-a-D-elythro-pentofuranosy1)heno [2,3-djpyrimidine-2,4(1H,3H)- dione 343 and 1 -(3-azido-2,3-dideoxy-P-D-erythro-pentofuranosyl )thieno[ 2,3- d Ipynmidine-2,4( 1 H,3H )-dione 344. 1 -(3-Azido-2,3-dideoxy- P -D-erythro-pentofuranosy1)-6-methy 1 quinazoline-2,4 ( 1 H,3H )-dione 5qb was treated with triphenylphosphine in pyndme followed by hydrolysis with concentrated aqueous ammoina to afford1 - (3-amino-2,3-dideoxy- P -D-erythro-pentofuranosy1)-6-methyl quinazoline- 2,4(1 H,3H)-&one - 345 whch was also obtained when 6-methylquinazoline-2,4( 1 H,3H )-&one - 8b silylated and condensed with 1,5-di-0-acetyl-2,3-dideoxy-3- phthahrmdo- P -D-erythro-pentohanose 346 which was prepared by reaction of phthalimide with 2-deoxy-D-ribose 332 using the P,O,, 1 H,O In-Bu,N reagent in CHC, followed by acetylation. Deprotection of the obtained 3-phthalimido nucleoside (347) with methylamine in absolute ethanol gave 345 and its anomeric mixture with the corresponding a -anomer 348. 1 -(3 -Amino-2,3-dideoxy- P -D-erythro-pentofuranosyl)thieno[2,3-d ] pynrmhe-2,4( 1H73H )-dione 349 was synthesized when its corresponding 3’- azido nucleoside 344 was treated with triphenylphosphine in pyridine followed by hydrolysis with concentrated aqueous ammonia . The 3’-amino nuclcoside 349 was obtained by another pathway when thieno [2,3-dl-pyrimidine-2,4( - lH,3H)&one 56 was silylated and condensed with 346 followed by deprotection with methylamine in absolute ethanol . 0 I I Quinazoline-2,4( 1H,3H )-dione 8 were silylated with HMDS and condensed with methyl 5-azido-2,5-dideoxy-3-0-( 4-methylbenzoyl )-a, P -Derythro- pentofuranoside m, which was prepared from 2-deoxy-D-ribose 332 by treatment with HC1 in methanol followed by reaction with sodium azide in the presence of carbon tetrabromide in DMF and subsequent acylation with 4- methylbenzoyl chloride in pyridine , using TMS triflate as the catalyst to afford 1 (5-azido-2,5-dideoxy-3-0-(4-methylbenzoy1)- a, P -D-erythro-pentofuranosyl) quinazoline-2,4( 1H,3H )-diones 357. 0.