Synthesis of glycosyl boranes and glycosyl borinates†

Vasella, Andrea; Wenger, W.J.; Rajamannar, T.

doi:10.1039/a906400a

Cited by 12 publications

(10 citation statements)

References 13 publications

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“…Before t ϭ 50 min, this signal overlapped that of H16 of 5. A singlet at δ ϭ 8.13 ppm, consistent with a BϪOH proton [18] indicated the formation of the borinic acid ϾBϪOH (ϾBϪ ϭ 9-BBN).…”

Section: Resultsmentioning

confidence: 92%

“…[18] This quadruplet was apparent from t ϭ 10 min, and rapidly gained in intensity to reach an almost stable level within the interval t ϭ 30Ϫ50 min, after which, it slowly faded out, while at the same time, the signals corresponding to 8 increased proportionally. The vicinal methyl (Me23 2 ) was difficult to locate, due to signal overlapping.…”

Section: Resultsmentioning

confidence: 95%

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Short Synthesis of New 23‐Vinyl Steroid Derivatives from Sapogenins by the Action of 9‐BBN on Vinylogous Esters

et al. 2004

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Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 95%

Short Synthesis of New 23‐Vinyl Steroid Derivatives from Sapogenins by the Action of 9‐BBN on Vinylogous Esters

et al. 2004

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“…Vasella et al [71][72][73] showed that the insertion of glycosylidene carbenes into a boron-carbon bond of BEt 3 led to unstable glycosyl boranes, while insertion into a boron-carbon bond of boronic esters yielded stable anomeric glycosyl borinates. The glycosylidene carbenes were generated by thermolysis or photolysis of glycosylidene diazirines.…”

Section: Synthesis Of Glycosyl Boranes and Borinatesmentioning

confidence: 99%

Boranes in Organic Chemistry 1. α-Carbonylalkyl- and β-Oxyalkylboranes in Organic Synthesis

Dembitsky

Толстиков

Srebnik

2017

Eurasian Chem. Tech. J.

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This review is devoted to the synthesis of α-carbonylalkyl-and β-hydroxy-alkyl boranes and their use in organic synthesis. α-Carbonyl-alkylboranes include several heteroatomic compounds, in particular, [1.2.3]-diazaborinines, uracyl boronic acids, and [1.2.3.4]diaza-diboretes. The latter type has been obtained by the ketene aminoborations. The reactions of halogenboranes with diazoesters and sulfur ylides resulting in formation of α-carbonyl alkylborates containing diazofunction or ylide structural fragment are described. Amino and halogen boration of acetylenic acid esters was also used for the synthesis of α-carbonyl alkyl boranes. Reactions involving Cr-carbene complexes and acetylenic borone esters were presented for the synthesis of naphthoquinone boronic acids. The formation of amidoboranes by boration of dichloroacetanilides was remined. Boration of 4,8-dimethoxy-2-quinolone with trimethylborates leading to 2-quinolone-3-boronic acid was described. The common synthetic method to α-carbonyl alkyl boranes based on the hydroboration of acrylic acid derivatives was discussed. The results of enhydrazones hydroboration, leading to stable cyclic complexes have been mentioned. The interaction of α-bromoketones with trialkyl or dialkylboranes represents as a general synthetic method to α-carbonyl alkyl boranes. Synthetic approaches to β-hydroxy alkyl boranes are performed. The wide spread hydroboration of vinyl and allyl esters received a well-described attention. The hydroboration of cyclanone enol acetates, 3-keto-and 17-keto-steroids and cyclic allyl alcohol acetates was discussed. The results of aliphatic and alicyclic vinyl esters (including dihydrofuran derivatives) boralylation leading to β-hydroxy alkyl boranes have been envisaged. The synthesis of optically active β-hydroxy alkyl boranes using chiral borane hydrides was discussed. The heterocyclic boran dihydrides are obtained by the hydroboration of dihydropyranes, chromenes and flavenes. Borosilylation of allyl allenylic esters was also been envisaged. The synthetic scheme to optically active boranes and further optically active alcohols were presented. The problems of selectivity regularities in hydroboration reaction by intermolecular complex formations have been discussed.

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“…We have already briefly reported [1] the insertion of the glycosylidene carbene 2 into the BÀalkyl bond of B-alkyl-9-oxa-10-borabicyclo [3.3.2]decanes that lead to stable glycosylborinates, and into a BÀC bond of BEt 3 to yield unstable glycosylboranes, which were transformed further by oxidation, elimination, or rearrangements. We now describe details of these reactions, additional transformations, and the crystal structure of a glycosylborinate that possesses an equatorial BÀC bond.…”

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“…Due to the almost anti-periplanar orientation of the C(1')ÀC (2') and the C(1)ÀC(2) bonds in both conformers, one HÀC(1') is oriented towards HÀC(3) and HÀC(5) (distance: 2.1 ± 2.3 ; Table 1). The anti-periplanar orientation of the C(1')ÀC (1) bond and the 4-chlorophenethyl substituent leads to a short distance between one HÀC(2') and HÀC(5) (2.34/2.66 ; Table 1). NOEs for the borinates 9 and 19 imply a b-d-configuration and indicate a similar position of the 4-chlorophenethyl substituent in solution as in the solid state of 17: one HÀC(1') signal is enhanced upon irradiation at C(3) or C (5), and one HÀC(2') signal is enhanced upon irradiation at C(5), as depicted for 19 (Fig.…”

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confidence: 99%

Glycosylidene Carbenes, Part 29 , Insertion into B−C and Al−C Bonds: Glycosylborinates, -boranes, and -alanes

Wenger

Vasella

2000

HCA

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Insertion of the glycosylidene carbenes derived from the diazirines 1, 14, and 15 into the BÀalkyl bond of the B-alkyl-9-oxa-10-borabicyclo[3.3.2]decanes 5, 6, and 7 yielded the stable glycosylborinates 8/9 (55%, 55 : 45), 10/11 (31%, 65 : 35), 12/13 (47%, 60 : 40), 16/17 (55%, 55 : 45), 18/19 (47%, 45 : 55), and 20/21 (31%, 30 : 70). Crystal-structure analysis of 17 and NOEs of 9 and 19 show that 17, 9, and 19 adopt similar conformations. The glycosylborinates are stable under acidic, basic and thermal conditions. The unprotected glycosylborinate 25 was obtained in 80% by hydrogenolysis of 12. Insertion of the glycosylidene carbene derived from the diazirine 1 into a BÀC bond of BEt 3 , BBu 3 , and BPh 3 led to unstable glycosylboranes that were oxidised to yield the hemiacetals 29 (55%), 31 (45%), and 33 (48%), respectively, besides the glucals 30 (13%), 32 (20%), and 34 (20%), respectively. Insertion of the glycosylidene carbenes derived from 14 and 15 into a BÀC bond of BEt 3 led exclusively to hemiacetals; only 15 yielding traces of the glucal 40 besides the hemiacetal 39. The glycosylidene carbene derived from 1 reacted with Al( i Bu) 3 and AlMe 3 to generate reactive glycosylalanes that were hydrolysed, yielding the C-glycosides 46 (21%) and 49 (30%), respectively, besides the glucals 48 (26%) and 51 (30%); deuteriolysis instead of protonolysis led to the monodeuterio analogues of 46 and 49, respectively, which possess an equatorial 2 H-atom at the anomeric center.Introduction. ± Glycosylidene carbenes, generated by thermolysis or photolysis of diazirines, insert into XÀH bonds to form O-, C-, and N-glycosides [2 ± 6], glycosylphosphines [7], and glycosylstannanes [8].We considered that the nucleophilic attack 2 ) of glycosylidene carbenes (e.g., 2) on triligated B or Al derivatives should lead to tetraligated intermediates, such as the Bylide 3 (Scheme 1). These ylides are expected to undergo (axial or equatorial) migration of a B or Al substituent, respectively, as shown in Scheme 1 for glycosylboranes 4, by analogy to the known migration of a B substituent in tetraligated borates that possess a vicinal leaving group [12] [13]. They should lead to C(1)-substituted

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Synthesis of glycosyl boranes and glycosyl borinates†

Cited by 12 publications

References 13 publications

Short Synthesis of New 23‐Vinyl Steroid Derivatives from Sapogenins by the Action of 9‐BBN on Vinylogous Esters

Short Synthesis of New 23‐Vinyl Steroid Derivatives from Sapogenins by the Action of 9‐BBN on Vinylogous Esters

Boranes in Organic Chemistry 1. α-Carbonylalkyl- and β-Oxyalkylboranes in Organic Synthesis

Glycosylidene Carbenes, Part 29 , Insertion into B−C and Al−C Bonds: Glycosylborinates, -boranes, and -alanes

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