PubMed:3378230 JSONTXT

{"project":"sentences","denotations":[{"id":"TextSentencer_T1","span":{"begin":0,"end":96},"obj":"Sentence"},{"id":"TextSentencer_T2","span":{"begin":97,"end":397},"obj":"Sentence"},{"id":"TextSentencer_T3","span":{"begin":398,"end":754},"obj":"Sentence"},{"id":"TextSentencer_T4","span":{"begin":755,"end":934},"obj":"Sentence"},{"id":"TextSentencer_T5","span":{"begin":935,"end":1169},"obj":"Sentence"},{"id":"TextSentencer_T6","span":{"begin":1170,"end":1320},"obj":"Sentence"},{"id":"TextSentencer_T7","span":{"begin":1321,"end":1546},"obj":"Sentence"},{"id":"TextSentencer_T8","span":{"begin":1547,"end":1657},"obj":"Sentence"},{"id":"T1","span":{"begin":0,"end":96},"obj":"Sentence"},{"id":"T2","span":{"begin":97,"end":397},"obj":"Sentence"},{"id":"T3","span":{"begin":398,"end":754},"obj":"Sentence"},{"id":"T4","span":{"begin":755,"end":934},"obj":"Sentence"},{"id":"T5","span":{"begin":935,"end":1169},"obj":"Sentence"},{"id":"T6","span":{"begin":1170,"end":1320},"obj":"Sentence"},{"id":"T7","span":{"begin":1321,"end":1546},"obj":"Sentence"},{"id":"T8","span":{"begin":1547,"end":1657},"obj":"Sentence"}],"namespaces":[{"prefix":"_base","uri":"http://pubannotation.org/ontology/tao.owl#"}],"text":"Synthesis of a close analog of the repeating unit of the antifreeze glycoproteins of polar fish.\nThe protected glycopeptide N-(benzyloxycarbonyl)-L-alanyl-[O-(2,3,4,6-tetra-O-benzoyl-beta-D- galactopyranosyl)-(1----3)-O-(2,4,6-tri-O-benzyl-alpha-D-galactopyranosy l)- (1----3)]-L-threonyl-L-alanine 2,2,2-trichloroethyl ester was made by coupling the respective disaccharide and tripeptide blocks. The disaccharide block was generated by coupling tetra-O-benzoyl-alpha-D-galactopyranosyl bromide to allyl 2,4,6-tri-O-benzyl-alpha-D-galactopyranoside and converting the product into O-(2,3,4,6-tetra-O-benzoyl-beta-D-galactopyranosyl)-(1----3)-2,4,6-tri-O -benzyl - alpha-D-galactopyranosyl chloride via the 1-propenyl glycoside and the free (1-OH) sugar. Alternatively, the 1-propenyl intermediate was obtained directly by using 1-propenyl 2,4,6-tri-O-benzyl-alpha-D-galactopyranoside as the acceptor in the initial coupling reaction. An efficient 3-step synthesis of 10 was accomplished by the dibutyltin oxide-assisted, selective crotylation of allyl alpha-D-galactopyranoside at O-3, followed by benzylation and treatment of the product with potassium tert-butoxide. The N-benzyloxycarbonyl (Z) and N-tert-butoxycarbonyl (Boc) 2,2,2-trichloroethyl esters of Thr-Ala and Ala-Thr-Ala were formed by sequential coupling. The silver triflate-promoted glycosylation of the Z-protected dipeptide and tripeptide by 2,3,4,6-tetra-O-benzyl-alpha-D-galactopyranosyl chloride, and of the tripeptide by 6, proceeded with excellent alpha-stereoselectivity. From the disaccharide tripeptide 21, the carboxyl-deprotected and fully deprotected derivatives were prepared."}

{"project":"NCBITAXON","denotations":[{"id":"T1","span":{"begin":91,"end":95},"obj":"OrganismTaxon"},{"id":"T7","span":{"begin":167,"end":174},"obj":"OrganismTaxon"},{"id":"T8","span":{"begin":447,"end":454},"obj":"OrganismTaxon"},{"id":"T9","span":{"begin":593,"end":600},"obj":"OrganismTaxon"},{"id":"T10","span":{"begin":1419,"end":1426},"obj":"OrganismTaxon"}],"attributes":[{"id":"A1","pred":"db_id","subj":"T1","obj":"117565"},{"id":"A2","pred":"db_id","subj":"T1","obj":"117569"},{"id":"A3","pred":"db_id","subj":"T1","obj":"118072"},{"id":"A4","pred":"db_id","subj":"T1","obj":"7777"},{"id":"A5","pred":"db_id","subj":"T1","obj":"7878"},{"id":"A6","pred":"db_id","subj":"T1","obj":"7898"},{"id":"A7","pred":"db_id","subj":"T7","obj":"100829"},{"id":"A8","pred":"db_id","subj":"T8","obj":"100829"},{"id":"A9","pred":"db_id","subj":"T9","obj":"100829"},{"id":"A10","pred":"db_id","subj":"T10","obj":"100829"}],"text":"Synthesis of a close analog of the repeating unit of the antifreeze glycoproteins of polar fish.\nThe protected glycopeptide N-(benzyloxycarbonyl)-L-alanyl-[O-(2,3,4,6-tetra-O-benzoyl-beta-D- galactopyranosyl)-(1----3)-O-(2,4,6-tri-O-benzyl-alpha-D-galactopyranosy l)- (1----3)]-L-threonyl-L-alanine 2,2,2-trichloroethyl ester was made by coupling the respective disaccharide and tripeptide blocks. The disaccharide block was generated by coupling tetra-O-benzoyl-alpha-D-galactopyranosyl bromide to allyl 2,4,6-tri-O-benzyl-alpha-D-galactopyranoside and converting the product into O-(2,3,4,6-tetra-O-benzoyl-beta-D-galactopyranosyl)-(1----3)-2,4,6-tri-O -benzyl - alpha-D-galactopyranosyl chloride via the 1-propenyl glycoside and the free (1-OH) sugar. Alternatively, the 1-propenyl intermediate was obtained directly by using 1-propenyl 2,4,6-tri-O-benzyl-alpha-D-galactopyranoside as the acceptor in the initial coupling reaction. An efficient 3-step synthesis of 10 was accomplished by the dibutyltin oxide-assisted, selective crotylation of allyl alpha-D-galactopyranoside at O-3, followed by benzylation and treatment of the product with potassium tert-butoxide. The N-benzyloxycarbonyl (Z) and N-tert-butoxycarbonyl (Boc) 2,2,2-trichloroethyl esters of Thr-Ala and Ala-Thr-Ala were formed by sequential coupling. The silver triflate-promoted glycosylation of the Z-protected dipeptide and tripeptide by 2,3,4,6-tetra-O-benzyl-alpha-D-galactopyranosyl chloride, and of the tripeptide by 6, proceeded with excellent alpha-stereoselectivity. From the disaccharide tripeptide 21, the carboxyl-deprotected and fully deprotected derivatives were prepared."}