(16.X.9 1)The benzyl-and the acyl-protected glyconolactone tosylhydrazones 6, 9, 12, 16, and 19 (Scheme I ) were prepared in good yields by treating the hemiacetals 4, 7, 10, 14, and 17 with N-tosylhydrazine, to give the N-glycosylhydrazines 5,8,11,15, and 18, and by oxidizing these hydrazines withN-bromosuccinimide (NBS) in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), with CrO,aipyridine complex or with pyridinium dichromate. Photolysis of the sodium salt 20 of 6 (Scheme 2) in the presence of N-phenylmaleimide, dimethyl fumarate, or acrylonitrile gave the corresponding cyclopropanes 21-28 in satisfactory yields. Photolytic or thermolytic glycosidation of phenol and 4-methoxyphenol by 20 yielded the anomeric glycosides 29/30 and 31/32, yields being marginally higher for the thermolytic process. Photolytic glycosidation of propan-2-01 gave the glycosides 33 and 34 in low yields only. Yields and ratios of products were compared to those obtained with the diazirine 1 as a source of glycosylidene carbenes. While the yields from 20 are lower, the ratios of products obtained in the photolytic reactions are in agreement with the formation of a common intermediate from both carbene precursors.
Dedicated to Professor Jack D. Dunitz on the occasion of his 80th birthdayThe diastereoselectivity of the addition of NH 3 and MeNH 2 to glyconolactone oxime sulfonates and the structures of the resulting N-unsubstituted and N-methylated glycosylidene diaziridines wereThe 15 N-labelled glucono-and galactono-1,5-lactone oxime mesylates 1* and 9* add NH 3 mostly axially (> 3 : 1; Scheme 4), while the 15 N-labelled mannono-1,5-lactone oxime sulfonate 19* adds NH 3 mostly equatorially (9 : 1; Scheme 7). The 15 N-labelled mannono-1,4-lactone oxime sulfonate 30* adds NH 3 mostly from the exo side (> 4 :1; Scheme 9). The configuration of the N-methylated pyranosylidene diaziridines 17, 18, 28, and 29 suggests that MeNH 2 adds to 1, 9, 19, and 23 mostly to exclusively from the equatorial direction (> 7 : 3; Schemes 5 and 8). The mannono-1,4-lactone oxime sulfonate 30 adds MeNH 2 mostly from the exo side (85 : 15; Scheme 10), while the ribo analogue 37 adds MeNH 2 mostly from the endo side (4 : 1; Scheme 10). Analysis of the preferred and of the reactive conformers of the tetrahedral intermediates suggests that the addition of the amine to lactone oxime sulfonates is kinetically controlled. The diastereoselectivity of the diaziridine formation is rationalized as the result of the competing influences of intramolecular H-bonding during addition of the amines, steric interactions (addition of MeNH 2 ), and the kinetic anomeric effect.The diaziridines obtained from 2,3,5-tri-O-benzyl-d-ribono-and -d-arabinono-1,4-lactone oxime methanesulfonate (42 and 48; Scheme 11) decomposed readily to mixtures of 1,4-dihydro-1,2,4,5-tetrazines, pentono-1,4-lactones, and pentonamides.The N-unsubstituted gluco-and galactopyranosylidene diaziridines 2, 4, 6, 8, and 10 are mixtures of two trans-substituted isomers (S/R ca. 19 :1, Scheme 2). The main, (S,S)-configured isomers S are stabilised by a weak intramolecular H-bond from the pseudoaxial NH to ROÀC(2). The diaziridines 12, derived from GlcNAc, cannot form such a H-bond; the (R,R)-isomer dominates (R/S 85 : 15; Scheme 3). The 2,3-di-O-benzyld-mannopyranosylidene diaziridines 20 and 22 adopt a 4 C 1 conformation, which does not allow an intramolecular H-bond; they are nearly 1 : 1 mixtures of R and S diastereoisomers, whereas the O H 5 conformation of the 2,3:5,6-di-O-isopropylidene-d-mannopyranosylidene diaziridines 24 is compatible with a weak H-bond from the equatorial NH to OÀC(2); the (R,R)-isomer is favoured (R/S ! 7 : 3; Scheme 6). The mannofuranosylidene diaziridine 31 completely prefers the (R,R)-configuration (Scheme 9).
Dedicated to the memory of Jorge F. Lo¬pez-Herrera Acylation and sulfonylation of the N,N'-unsubstituted glucosylidenespirodiaziridines 1A/1B 95 : 5 with Ac 2 O, BzCl, FmocCl, TsCl, (naphthalen-2-yl)sulfonyl, and (2,4,6-triisopropylphenyl)sulfonyl chloride, and concomitant rearrangement gave the acylated and sulfonylated gluconolactone hydrazones 2B ± 2G in 40 ± 83% yield (Scheme 2). Similarly, the galacto and manno analogues 3A/3B 95 : 5 and 5A/5B 55 : 45 and the mannofuransoylidene-diaziridine 30 were acetylated and tosylated to give 4A, 4B, 6, 31A, and 31B (55 ± 73% yield; Schemes 2 and 5). 15 N-Labelling of 11A/11B and 14A/14B showed that the pseudoequatorial NH of the gluco diaziridines 1 and the pseudoaxial NH of the galacto diaziridines 3 were preferentially acetylated and tosylated (Scheme 3). Sulfonylation of the N-methylated diaziridines 19A/19B 72 : 28, 22A/22B 85 : 15, 25A/25B 85 : 15, 28A/28B 80 : 20, and 33A/33B/33C/33D 76 : 4 : 12 : 8 yielded the N-methyl-N-tosylglyconolactone hydrazones 20, 23, 26, 29, and 34 (44 ± 66%; Schemes 4 and 5). The methylated N-atom of the diaziridines proved more reactive, irrespective of the configuration at C(2) and C(4). The products were readily hydrolysed to glyconolactones.Introduction. ± The reactivity of glycosylidene diaziridines has not been wellexplored. Apart from an investigation of their formation [1], with special emphasis on the stereoselectivity of the addition of NH 3 and MeNH 2 to the precursor glyconolactone oxime sulfonates [2], only the oxidation of these diaziridines with iodine and Et 3 N or Me 3 N in MeOH, Et 2 O, or CH 2 Cl 2 [3] to N-unsubstituted-glycosylidene diazirines was investigated. These diazirines have been studied as precursors of glycosylidene carbenes [3 ± 5].The reactivity of 3-alkyldiaziridines has been explored more extensively. Their reaction with electrophiles is strongly influenced by the nature of the electrophile and by the N-substituents. Attack of electrophiles on the diaziridines I leads to diaziridinium ions II (Scheme 1). For R 3 H, deprotonation of II afforded substituted diaziridines III [6 ± 10]. Alternatively, diaziridine ring opening of II led to the hydrazonium ions IV, which were transformed into hydrazones V (R 4 H) [11] [12] and into azomethine imines VI (R 3 H) [13]. Hydrolysis of IV afforded ketones VII and hydrazines VIII [13a] [14] [15]. This transformation to hydrazines constitutes a valuable method for the selective preparation of otherwise hardly accessible N -alkyland N,N'-dialkylhydrazines [16]. The reaction of 1,3,3-trimethyldiaziridine with AcCl led to a 4 : 1 mixture of N-methyl-N'-isopropylidene-acethydrazide and 2-acetyl-1,3,3trimethyldiaziridine [17].Except for the oxidation with I 2 , we found no reaction of glycosylidene diaziridines, nor of any other 3-alkoxydiaziridine with electrophiles. We have examined the reactions of glycosylidene-diaziridines with acylating and sulfonylating reagents, and describe the results of these experiments.Results and Discussion. ± 1. Acylation and Sulfonylation...
The W -(glycofuranosylidene)toluene-4-sulfonohydrazides 5 and 10 (Scheme I ) were prepared in good yields by oxidation (1,3-dibromo-5,5-dimethylhydantoin/Et3N) of the W -glycosyltoluene-4-sulfonohydrazides 4 and 9, which were obtained from 2,3,5-tri-0-benzyl-o-ribose (3) and 2,3,5-tri-O-benzyI-o-arabinos.e (8), respectively, and toluene-4-sulfonohydrazide. The analogous naphthalene-2-sulfonohydrazides 7 and 12 were similarly prepared from 3 and 8 via 6 and 11. Photolysis in the presence of phenol of the sodium salt 15 (Scheme 2), best generated in situ, yielded the anomeric glycosides 16, some 5, and traces of the glycosides ( Introduction. -Glycopyranosylidene carbenes, known reactive intermediates [ 11, are best generated from diazirines, such as 1, under mild thermal and photochemical conditions [2]. They are also formed from the alkali salts of N'-glycosylidenesulfonohydrazides, such as 2 [3] [4], or (in low yields) from diazides under photochemical conditions [5]. N' -(Glycopyranosylidene)sulfonohydrazides are more readily prepared than the corresponding diazirines and are more stable. Their salts react similarly to diazirines in forming glycosides with phenols [&9] and cyclopropanes with electron-deficient alkenes [3] [9] [lo]. Thermolysis of N' -(glycopyranosylidene)sulfonohydrazides, however, also generates sulfinates, and this results in the formation of additional by-products [I 11 [12].
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