Die Struktur der Drevogenine. 2. Mitteilung Struktur von Drevogenin P. Glykoside und Aglykone, 278. Mitteilung

Drevogenin A was converted in several steps (acetylation, hydrogenation, dehydration, hydrogenation, the haloform reaction and energetic alkaline hydrolysis) into 3β, 11α, 12β-trihydroxy-5α-etianic acid, which could be characterised by its crystalline methyl ester ( 15 ) and its tri-O-acetyl methyl ester ( 16 ). The same acid was obtained by partial synthesis starting from hecogenin. Taking into consideration earlier results [1], the structure of drevogenin P is proved to be 3β, 11α, 12β, 14β-tetrahydroxy-20-oxo-Δ⁵-pregnene ( 7 ). Energetic hydrolysis of dihydro-3-O-acetyldrevogenin A gave a mixture of 17αH- and 17βH-desacyl-kondurangogenin A, which were obtained in crystalline form after separation by chromatography. The only difference between the basic structures of the drevogenins and kondurangogenin A is the presence of a double bond in the 5-position in the former.     

Synthetic transformations of isoquinoline alkaloids. Synthesis of 1-halo derivatives of <Emphasis Type="Italic">endo</Emphasis>-ethenotetrahydrothebaine and their behavior in the heck reaction

Bromination of endo-ethenotetrahydrothebaine derivatives having a pyrrolidine ring fused at the C⁷-C⁸ bond, namely 1′-substituted 4,5α-epoxy-6α,14-etheno-3,6-dimethoxy-17-methyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]morphinan-2′,5′-diones, 1′-aryl-4,5α-epoxy-6α,14-etheno-3,6-dimethoxy-17-methyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]morphinans, and 4,5α-epoxy-6α,14-etheno-2′α-hydroxy-3,6-dimethoxy-17-methyl-1′-phenyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]morpphinan-5′-one, with molecular bromine in formic acid smoothly afforded the corresponding 1-bromo derivatives. Iodination of 4,5α-epoxy-6α,14-etheno-3,6-dimethoxy-17-methyl-1′-phenyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]-4,5α-epoxy-6α,14-etheno-3,6-dimethoxy-17-methyl-1′-phenyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]-morphinan-2′,5′-dione with iodine(I) chloride gave 4,5α-epoxy-6α,14-etheno-1-iodo-3,6-dimethoxy-17-methyl-1′-phenyl-2′,5′,7β,8β-tetrahydro-1′H-14α-pyrrolo[3′,4′:7,8]morphinan-2′,5′-dione. The resulting 1-halo derivatives were brought into the Heck reaction with acrylic acid esters to obtain 1-[(E)-2-(alkoxycarbonyl)ethenyl]-substituted compounds. Demethylation of the 6-methoxy group in 1-bromo-endo-ethenotetrahydrothebaines was accomplished using boron(III) bromide in chloroform.     

Ozonolysis of alkenes and study of reactions of polyfunctional compounds: LXVIII.* synthesis of ω-carboxy derivatives of 20-hydroxyecdysone diacetonide

Ozonolysis of ω-anhydro-20-hydroxyecdysone diacetonide gave a mixture of 24- and 25-oxo derivatives, and only the first of these (23-carbaldehyde) reacted with malonic acid according to Knoevenagel to give 14α-hydroxy-2β,3β: 20,22-bis(isopropylidenedioxy)-6-oxo-27-nor-5β-cholesta-7,24-dien-26-oic acid. The oxidation of 23-carbaldehyde with ozone, followed by treatment with diazomethane, afforded 20-hydroxy-25,26,27-trinorecdysone-23-carboxylic acid methyl ester diacetonide.     

Base-catalyzed redox reactions of α-hydroxyalkylazaaromatic N-oxides

The (α-hydroxybenzyl)pyridine 1-oxides on heating with aqueous sodium hydroxide yielded the corresponding benzoylpyridines in redox reactions. When the phenyl groups of the foregoing compounds was replaced by hydrogen or methyl the redox reactions occurred less readily. A kinetic isotope effect of 3 was found for 4-(α-deuterio-α-hydroxybenzyl)pyridine 1-oxide on reaction with sodium hydroxide. The removal of the α-deuterio group is non-reversible. A mechanism consistent with these observations is given. 6-Acetoxyphenanthridine 5-oxide yielded with concentrated hydrochloric acid a redox product, 6-formylphenanthridine hydrochloride, whereas under the same conditions neither (α-hydroxybenzyl)pyridine 1-oxides nor 2-hydroxy-methylquinoline 1-oxide yielded a redox product.     

"Alpha"-, "beta"- and "delta"-anhydrodigitoxigenin

The syntheses of 3β-hydroxy-5β-carda-14, 20:22-dienolide (= «β»-anhydro-), 3β-hydroxy-5β-carda-8:14, 20:22-dienolide (= «α»-anhydro-) and «δ»-anhydro-digitoxigenin (= probably 3β-hydroxy-5β, 14β-carda-8, 20:22-dienolide) by the best ways known to date, have been described. «δ»-Anhydro-digitoxigenin represents the thermodynamically most stable isomer. In this isomer the double bond in position 8 is unaffected by hydrogenation with Pt in acetic acid; with perbenzoic acid an epoxide results from which, on hydrogenation, the double bond can be regenerated in its original position. Analogous reactions are known to occur in the 8:14-epoxides.     

5α-androstano [3,2-b]pyridines, 5α-androstano[17,16-b]pyridines and androst-4 and 5-eno[17,16-b]pyridines

A new synthesis of 5α-androstano[3,2-b]pyridin-17β-ol acetate (VIa) and 17-methyl-5α-androstano[3,2-b]pyridin-17β-ol (VIb), first reported by Shimizu, Ohta, Ueno, and Takegoshi, was achieved. The analogous 5α - androstano[17,16-b]pyridin-3β-ol (XII), 5α-androstano[17,16-b]pyridin-3-one (XIVa), and androst-4-eno[17,16-b]pyridin-3-one (XIVb) were also prepared. An illustration of the method follows. Condensation of 3β-hydroxy-5α-androstan-17-one (VIIa) with 3-(2-furyl)acrolein afforded 16-[3-(2-furyl)-2-propenylidene]-3β-hydroxy-5α-androstan-17-one (VIIIa), the oxime (IXa) of which was thermally cyclized to 5α-androstano[17,16-b]-6′-(2-furyl)pyridin-3β-ol (Xa). 3β-Hydroxy-5α-androstano[17,16-b]pyridine-6′-carboxylic acid (XI) was obtained by ozonolysis of Xa. Thermal decarboxylation of XI gave XII. Cinnamaldehyde was used in place of 3-(2-furyl)acrolein to give the corresponding phenylpyridines.     

Haloacetylated enol ethers. 7 . Synthesis of 3-aryl-5-trihalomethylisoxazoles and 3-aryl-5-hydroxy-5-trihalomethyl-4,5-dihydroisoxazoles

β-Aryl-β-methoxyvinyl trihalomethyl ketones 1a-g, 2a-g [aryl = p-YC₆H₄ where Y= H, Me, OMe, F, Cl, Br, NO₂] are cyclocondensed with hydroxylamine hydrochloride to afford the 3-aryl-5-hydroxy-5-trihalomethyl-4,5-dihydroisoxazoles 3a-g, 4a-f in good yield. The dehydratation of compounds 3a-g with concentrated sulfuric acid, led the corresponding 3-aryl-5-trichloromethylisoxazoles 5a-g . An alternative one-pot procedure yields 3-aryl-5-trihalomethylisoxazoles 5,6a-g directly by cyclocondesation of 1,2a-g with hydroxylamine hydrochloride in the presence of an excess of concentrated hydrochloric acid.     

Reductive degradation of nido-1-CB8H12 into smaller-cage carborane systems via new monocarbaboranes [arachno-5-CB8H13](-) and closo-2-CB6H8

Treatment of the nido-1-CB8H12 (1) carborane with NaBH4 in THF at ambient temperature led to the isolation of the stable [arachno-5-CB8H13]- (2(-)), which was isolated as Na+[5-CB8H13]-.1.5 THF and PPh4 +[5-CB8H13]- in almost quantitative yield. Compound 2(-) underwent a boron-degradation reaction with concentrated hydrochloric acid to afford the arachno-4-CB7H13 (3) carborane in 70 % yield, whereas reaction between 2(-) and excess phenyl acetylene in refluxing THF gave the [closo-2-CB6H7]- (4-) in 66 % yield. Protonation of the Cs+4(-) salt with concentrated H2SO4 or CF3COOH in CH2Cl2 afforded a new, highly volatile 2-CB6H8 (4) carborane in 95 % yield, the deprotonation of which with Et3N in CH2Cl2 leads quantitatively to Et3NH+[2-CB6H7](-) (Et3NH+4(-)). Both compounds 4- and 4 can be deboronated through treatment with concentrated hydrochloric acid in CH2Cl2 to yield the carbahexaborane nido-2-CB5H9 (5) in 60 % yield. New compounds 2-, 3, and 4 were structurally characterised by the ab initio/GIAO/MP2/NMR method. The method gave superior results to those carried out using GIAO-HF when relating the calculated 11B NMR chemical shifts to experimental data.     

Cardenolide and pregnane derivatives from the roots of Trachycalymma fimbriatum (Weimark) Bullock. Glycosides and aglycones. 322

The roots of Trachycalymma fimbriatum (WEIMARCK ) BULLOCK contain both cardenolide and pregnaneglycosides. Elimination of 2-deoxysugars by mild acid hydrolysis gave a mixture from which some anhydroderivatives and the following compounds could be isolated: uzarigenin ( l ), ascleposide = 3-O-(6-deoxy-β-D -allopyranosyl)-uzarigenin ( 4 ), coroglaucigenin ( 6 ) and two pregnane derivatives (H and J). Compound H could be identified as 3β,14β-dihydroxy5α, 17α-pregnan-20-one ( 10 ). Compound J is probably a new substance, for which we tentatively assign structure 18 , i.e. 3β8β,14β-trihydroxy-5α,17α-pregnan-20-one. We suspect H and J to be artefacts produced from the corresponding 17b-derivatives during acid hydrolysis. 17-iso-H is probably a precursor in the biosynthesis of uzarigenin. The cardenolides of Trachycalymma fimbriatum are the same as found in Asclepias glaucophylla, a closely related species, while the pregnane derivatives of the latter are distinctly higher hydroxylated.     

Furopyridines. VIII. Molecular structure and two-dimensional NMR spectral assignment of 2,14-dimethyl-8aβ-hydroxy-7,10-dioxo-5β,6β-(propano)-6α,8α-(ethanoimino)-trans-perhydroisoquinoline

This paper reports the two-dimensional nmr spectral assignment and the X-ray structural determination of 2,14-dimethyl-8β-hydroxy-7,10-dioxo-5β,6β-(propano)-6α,8α-(ethanoimino)-trans-perhydroisoquinoline V which was obtained from 7,10-dimethyl-2β-hydroxy-14-oxo-2,3-(methanoiminoethano)-3β,4β-(propano)-3,4,5,6,7,8-hexahydro-2H-pyrano[2,3-c]pyridine IV by isomerization with hydrochloric acid. Both the compounds IV and V afforded the same dimethiodide IV -2MeI, while the configurational isomer 2,14-dimethyl-8aβ-hydroxy-7,10-dioxo-5α,6β-(propano)-6α,8α-(ethanoimino)-trans-perhydroisoquinoline III gave monomethiodide III -Mel. The structures of these methiodides were also confirmed by X-ray analysis.     

Chemical studies of carbohydrates. Part I. Conversion of derivatives of glucose and allose into pyrazoles and pyridazines

On reaction of 1,2:5,6-di-O-isopropylidenc-3-O-(p-tolylsulfonyl)-α-D-glueofuranose ( 1 ) with hydrazine hydrate at 140° besides formation of 3-deoxy-3-hydrazino-1,2:5,6-di-O-isopropylidene-α-D-allofuranose ( 2 ) and 3-dcoxy-1,2:5,6-di-O-isopropylidene-α-D-erythro-hex-3-enofuranose ( 3 ), ring transformation into 3-[4′-(2′,2′-dimethyl-1′,3′-dioxolanyl)]pyridazine ( 4 ) takes place. At 170°, however, only 2 and 4 are formed, indicating that 3 is the precursor of 4. Treatment of 3 with hydrazine hydrate at 170° indeed gives a nearly quantitative ring expansion into 4. Treatment of 3-dcoxy-3-hydrazino-1,2:5,6-di-O-isopropylidenc-α-D-glucofuranose ( 8 ) as well as the stereoisomeric allofuranose 2 with concentrated hydrochloric acid gives a nearly quantitative ring interconversion into 3-(D-erythro-trihydroxypropyl)pyrazole ( 9 ).     

Synthesis of pyrano[3,4-c]pyrazole and pyrazolo[3,4-d][1,2]diazepine derivatives

By the action of thionyl chloride on 3(5)-R-4-phenacylpyrazole-5(3)-carboxylic acid ( 3c,d ), 3-R-5-phenylpyrano[3,4-c]pyrazole-7-(1H)ones ( 4c,d ) were obtained. When 4c,d were treated with hydrazine hydrate followed by refluxing in ethanol containing acetic acid, 4,7-dihydro-3-R-5-phenylpyrazolo[3,4-d][1,2]-diazepin-8-(1H)ones ( 6c,d ) were formed. Compounds 6c,d , in turn, were refluxed in ethanol saturated with hydrochloric acid to yield 6-amino-1,6-dihydro-3-R-5-phenyl-7H-pyrazolo[3,4-c]pyridin-7-ones ( 7c,d ). Compounds 7c,d could be obtained directly from 5c,d. The starting materials 3c,d were prepared by hydrolysis of the oxime of 3(5)-R-4-phenacyl-5(3)carboalcoxypyrazoles ( 1a,b ). Structural assignments rested on correct elemental analysis, molecular weights determined by mass spectrometry, and spectroscopic evidence.     

Strukturelle Abwandlungen an partiell silylierten Kohlenhydraten mittels Triphenylphosphin/Azodicarbonsäure-diäthylester. 3. Mitteilung [1]

Structural Modification on Partially Silylated Carbohydrates by Means of Triphenylphosphine/Diethyl Azodicarboxylate Reaction of methyl 2, 6-bis-O-(t-butyldimethylsilyl)-β-D -glucopyranoside ( 1a ) with triphenylphosphine (TPP)/diethyl azodicarboxylate (DEAD) and Ph₃P · HBr or methyl iodide yields methyl 3-bromo-2, 6-bis-O-(t-butyldimethylsilyl)-3-deoxy-β-D -allopyranoside ( 3a ) and the corresponding 3-deoxy-3-iodo-alloside 3c (Scheme 1). By a similar way methyl 2, 6-bis-O-(t-butyldimethylsilyl)-α-D -glucopyranoside ( 2a ) can be converted to the 4-bromo-4-deoxy-galactoside 4a and the 4-deoxy-4-iodo-galactoside 4b . In the absence of an external nucleophile the sugar derivatives 1a and 2a react with TPP/DEAD to form the 3,4-anhydro-α- or -β-D -galactosides 5 and 6a , respectively, while methyl 4, 6-bis-O-(t-butyldimethylsilyl)-β-D -glucopyranoside ( 1b ) yields methyl 2,3-anhydro-4, 6-bis-O-(t-butyldimethylsilyl)-β-D -allopyranoside ( 7a , s. Scheme 2). Even the monosilylated sugar methyl 6-O-(t-butyldimethylsilyl)-α-D -glucopyranoside ( 2b ) can be transformed to methyl 2,3-anhydro-6-O-(t-butyldimethylsilyl)-β-D -allopyranoside ( 8 ; 56%) and 3,4-anhydro-α-D -alloside 9 (23%, s. Scheme 3). Reaction of 1c with TPP/DEAD/HN₃ leads to methyl 3-azido-6-O-(t-butyldimethylsilyl)-3-deoxy-β-D -allopyranoside ( 10 ). The epoxides 7 and 8 were converted with NaN₃/NH₄Cl to the 2-azido-2-deoxy-altrosides 11 and 13 , respectively, and the 3-azido-3-deoxy-glucosides 12 and 14 , respectively (Scheme 4 and 5). Reaction of 7 and 8 with TPP/DEAD/HN₃ or p-nitrobenzoic acid afforded methyl 2,3-anhydro-4-azido-6-O-(t-butyldimethylsilyl)-4-deoxy-α- and -β-D -gulopyranoside ( 15 and 17 ), respectively, or methyl 2,3-anhydro-6-O-(t-butyldimethylsilyl)-4-O-(p-nitrobenzoyl)-α- and -β-D -gulopyranoside ( 16 and 18 ), respectively, without any opening of the oxirane ring (s. Scheme 6). - The 2-acetamido-2-deoxy-glucosides 19a and 20a react with TPP/DEAD alone to form the corresponding methyl 2-acetamido-3,4-anhydro-6-O-(t-butyldimethylsilyl)-2-deoxy-galactopyranosides ( 21 and 22 ) in a yield of 80 and 85%, respectively (Scheme 7). With TPP/DEAD/HN₃ 20a is transformed to methyl 2-acetamido-3-azido-6-O-(t-butyldimethylsilyl)-2,3-didesoxy-β-D -allopyranoside ( 25 , Scheme 8). By this way methyl 2-acetamido-3,6-bis-O-(t-butyldimethylsilyl)-α-D -glucopyranoside ( 19b ) yields methyl 2-acetamido-4-azido-3,6-bis-O-(t-butyldimethylsilyl)-2,4-dideoxy-α-D -galactopyranoside ( 23 ; 16%) and the isomerized product methyl 2-acetamido-4,6-bis-O-(t-butyldimethylsilyl)-2-deoxy-α-D -glucopyranoside ( 19d ; 45%). Under the same conditions the disilylated methyl 2-acetamido-2-deoxy-glucoside 20b leads to methyl 2-acetamido-4-azido-3,6-bis-O-(t-butyldimethylsilyl)-2,4-dideoxy-β-D -galactopyranoside ( 24 ). - All Structures were assigned by ¹H-NMR. analysis of the corresponding acetates.     

arabinonucleosides

The α-D-arabinonucleosides of cytosine ( 6 ) and 5-fluorouracil ( 9 ) were prepared from the 2,3,-5-tri-O-benzoyl-D-arabinofuranosyl halides, in keeping with the trans rule. The 2′-O-methyl-)3-D-arabinonucleosides of 5-fluorouraeil (β- 14 ) and adenine (β- 21a ) were prepared from 3,5-di-O-(4-ehlorobenzoyl)-2-O-methyl-α-D-arabinofuranosyl chloride, although in both cases a lesser amount of the α-anomer was also found. Reaction of 3,5-di-O-(4-chlorobenzoyl)-2-deoxy-2-(methylthio)-α-D-arabinofuranosyl chloride, prepared in four steps from methyl 2,3-anhydro-α-D-ribofurano-side ( 15 ), with N-benzoyladenine gave slightly more of the β- than the α-arabinonucleoside 20b . The β-anomer was converted to 9-[2-deoxy-2-(methylthio)-β-D-arabinofuranosyl]adenine. Only 1-α-D-arabinofuranosylcytosine ( 6 ) proved to be cytotoxic.     

盐酸催化合成α-萘乙酸甲酯

以α-萘乙酸、甲醇为原料,以浓盐酸为催化剂,通过酯化反应合成了植物生长调节剂萘乙酸甲酯。通过正交设计讨论了醇酸摩尔比、催化剂用量、反应时间等因素对酯化产率的影响。在α-萘乙酸50mmol,n(甲醇)：n(α-萘乙酸)=25,催化剂用量为α-萘乙酸质量的17％,反应时间2．0h,酯化温度65℃～69℃的最佳反应工艺条件下,产率97．4％。     

Reaction of 2-dimethylaminomethylene-1,3-diones with dinucleophiles. X. synthesis of 5-substituted ethyl or methyl 4-isoxazolecarboxylates and methyl 4-(2,2-dimethyl-1-oxopropyl)-5-isoxazolecarboxylate

Reaction of ethyl or methyl 2-dimethylaminomethylene-3-oxoalkanoates with hydroxylamine hydrochloride in methanol solution afforded in high yields the relative esters of 5-substituted 4-isoxazolecarboxylic acids II . These esters were hydrolyzed generally with concentrated hydrochloric acid-acetic acid mixtures to the corresponding carboxylic acids in satisfactory yields. Ethyl or methyl esters II isomerized with sodium ethoxide or methoxide, respectively, to the corresponding esters or hemiesters of 2-cyano-3-oxoalkanoic acids generally in excellent to satisfactory yields. Reaction of methyl 5,5-dimethyl-3-dimethylaminomethylene-2,4-dioxohexanoate with hydroxylamine hydrochloride afforded in moderate yield methyl 4-(2,2-dimethyl-1-oxopropyl)-5-isoxazolecarboxylate, which was converted by acid hydrolysis as above to 4-t-butyl-4-hydroxyfuro[3,4-d]isoxazol-6-(4H)-one.     

Reactions of o-aminonitriles with isocyanates. 1. A two-step synthesis of 2,6-dihydroimidazo[1,2-c]quinazolin-5-(3H)one

The reaction of anthranilonitrile with 2-chloroethyl isocyanate yields 2-[3-(2-chloroethyl)ureido]benzo-nitrile ( 6 ) which, upon heating, or treatment with base, undergoes a double cyclization to form 2,6-dihydroimidazo[1,2-c]quinazolin-5-(3H) one ( 8 ) in excellent yield. When heated with hydrochloric acid, 6 is converted initially into 2-(2-chloroethylamino)-4H-[3,1]benzoxazin-4-one ( 18 ) and further into 3-(2-chloroethyl)-2,4-(1H,3H)quinazolinedione ( 15 ). The acid-catalyzed reaction of 2,3-dihydro-5H-oxazolo[2,3-b]quinazolin-5-one ( 14 ) with nucleophilic reagents yields 3-substituted 2,4-(1H,3H)quinazolinediones.     

A rapid microwave induced synthesis of [carboxyl-14C]-nicotinic acid (vitamin B3) and [carbonyl-14C]-nicotinamide using K14CN

Microwave assisted direct aromatic substitution of 3-bromopyridine with K¹⁴CN as the cyanide source and catalytic amount of tetrabutylammonium bromide afforded [3-¹⁴C]-cyanopyridine 3 in 90% yield. Microwave assisted hydrolysis of 3 with a mixture of concentrated hydrochloric acid and propionic acid afforded [carboxyl-¹⁴C]-nicotinic acid in 95% yield whereas microwave assisted hydrolysis of 3 with a mixture of concentrated sulfuric acid and propionic acid afforded [carbonyl-¹⁴C]-nicotinamide in 85% yield.     

2-Acyl(aroyl)-1,1,3,3-tetracyanopropenides: I. Synthesis of 2-[5-amino-2-aryl-2-chloro-4-cyanofuran-3(2H)-ylidene]-propanedinitriles by reaction of potassium 2-aroyl-1,1,3,3-tetracyanopropenides with concentrated hydrochloric acid

Potassium 2-aroyl-1,1,3,3-tetracyanopropenides reacted with concentrated hydrochloric acid to give the corresponding 2-[5-amino-2-aryl-2-chloro-4-cyanofuran-3(2H)-ylidene]propanedinitriles.     

Synthesis and ring-opening polymerization of new 1,4-anhydro-glucopyranose derivatives

Three new 1,4-anhydro-glucopyranose derivatives having different hydroxyl protective groups such as 1,4-anhydro-2,3,6-tri-O-methyl-α-D -glucopyranose (AMGLU), 1,4-anhydro-6-O-benzyl-2,3-di-O-methyl-α-D -glucopyranose (A6BMG), and 1,4-anhydro-2,3-di-O-methyl-6-O-trityl-α-D -glucopyranose (A6TMG) were synthesized from methyl α-D -glucopyranoside in good yields. Their polymerizability was compared with that of 1,4-anhydro-2,3,6-tri-O-benzyl-α-D -glucopyranose (ABGLU) reported previously. The trimethylated monomer, AMGLU, was polymerized by a PF₅ catalyst to give 1,5-α-furanosidic polymer having number-average molecular weights (M̄_n) in the range of 2.8 × 10³ to 6.8 × 10³. The ¹³C-NMR spectrum was compared with that of methylated amylose and cellulose. Other anhydro monomers, A6BMG and A6TMG, gave the corresponding 1,5-α furanosidic polymers having M̄_n = 17.1 × 10³ and 1.8 × 10³, respectively. Thus, the substituents at the C2 and C6 positions were found to play an important role for the ring-opening polymerizability of the 1,4-anhydro-glucose monomers. In addition, debenzylation of the tribenzylated polymer gave free (1 → 5)-α-D -glucofuranan. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 841–850, 1998