51450-36-3Relevant academic research and scientific papers
Practical preparation of mono- and di-O-isopropylidene derivatives of monosaccharides and methyl 4,6-O-benzylidene glycosides from free sugars in a deep eutectic solvent
Rokade, Sunil M.,Bhate, Prakash M.
, p. 20 - 30 (2017/09/25)
Free sugars were rapidly converted into the corresponding di-O-isopropylidene derivatives and methyl O-benzylidene glycosides in excellent yields and purity in a deep eutectic solvent made from choline chloride and malonic acid (ChCl:MA). Reaction conditions were mild; work-up was easy, and further purification was not necessary. Given the inexpensive, nontoxic, and recyclable nature of ChCl:MA, this protocol is environmental friendly.
Total synthesis of (-)-isatisine A via a biomimetic benzilic acid rearrangement
Xiao, Mingxing,Wu, Wei,Wei, Lin,Jin, Xiaojie,Yao, Xiaojun,Xie, Zhixiang
, p. 3705 - 3714 (2015/05/20)
The biomimetic total synthesis of potential anti-HIV (-)-isatisine A, a novel alkaloid with an unprecedented fused tetracyclic skeleton, was accomplished in eight steps from indole and known 4,6-O-isopropylidene-protected glucal. The synthetic strategy was inspired primarily by the proposed biogenetic hypothesis that indole C-furanoside would be derived from indole C-glucoside via a ring contractive benzilic acid rearrangement. The biogenetic hypothesis was enabled by model studies: the O-glucoside was converted to O-furanoside via a benzilic acid rearrangement.
σ-Ferrier rearrangement of carbohydrate derived vinylcyclopropanes: a facile approach to oxepane analogs
Ganesh, Venkataraman,Kundu, Taraknath,Chandrasekaran, Srinivasan
, p. 7268 - 7282 (2017/09/13)
This article presents our work on the σ-Ferrier ring-expansion of carbohydrate derived vinylcyclopropanes (VCPs) under electrophilic conditions mediated by chloramine-T and a phase-transfer catalyst. The present work serves as the first example on the stu
Total synthesis of (+)-papulacandin D
Denmark, Scott E.,Kobayashi, Tetsuya,Regens, Christopher S.
supporting information; experimental part, p. 4745 - 4759 (2010/08/06)
A total synthesis of (+)-papulacandin D has been achieved in 31 steps, in a 9.2% overall yield from commercially available materials. The synthetic strategy divided the molecule into two nearly equal sized subunits, the spirocyclic C-arylglycopyranoside and the polyunsaturated fatty acid side-chain. The C-arylglycopyranoside was prepared in 11 steps in a 30% overall yield from triacetoxyglucal. The fatty acid side-chain was also prepared in 11 steps in a 30% overall yield from geraniol. The key strategic transformations in the synthesis are: (1) a palladium-catalyzed, organosilanolate-based cross-coupling reaction of a dimethylglucal-silanol with an electron-rich and sterically hindered aromatic iodide and (2) a Lewis-base catalyzed, enantioselective allylation reaction of a dienal and allyltrichlorosilane. A critical element in the successful execution of the synthesis was the development of a suitable protecting group strategy that satisfied a number of stringent criteria.
Synthesis of pyranoid and furanoid glycals from glycosyl sulfoxides by treatment with organolithium reagents
Gomez, Ana M.,Casillas, Marta,Barrio, Aitor,Gawel, Anna,Lopez, J. Cristobal
experimental part, p. 3933 - 3942 (2009/04/08)
Glycosyl sulfoxides can be conveniently transformed into pyranoid or furanoid glycals by treatment with organolithium reagents. The more likely reaction pathway involves a sulfoxide/metal exchange reaction to generate a glycosyllithium derivative that und
Organotransition metal modified sugars: Part 22. Direct metalation of glycals: Short and efficient routes to diversely protected stannylated glycals
J?kel, Christoph,D?tz, Karl Heinz
, p. 172 - 185 (2007/10/03)
A complete set of D-hexose-derived silyl and isopropylidene/silyl-protected glycals bearing complementary configurations at C-3 and C-4 has been synthesized in short and efficient 1-3 step sequences from standard precursors. The glycals have been applied to metalation reactions to give storable vinyl lithium equivalents by subsequent transmetalation to vinyl stannanes which represent valuable intermediates for transition metal-catalyzed cross-coupling reactions. A 1H-NMR-assisted conformational analysis has been carried out with the protected glycals and the stannylated congeners. The isopropylidene/silyl-protected glycals adopt the 4H5-conformation caused by the bicyclic system, whereas the conformations of the fully silyl-protected monocyclic glycals are mainly controlled by the vinylogous anomeric effect. The discussed galactal- and allal-derivatives show dynamic behaviour on the NMR-time-scale. At low temperatures the two possible conformers (4H5 and 5H4) have been observed demonstrating competition of steric congestion and stereoelectronic interaction via the vinylogous anomeric effect (VAE).
Organotransition-metal-modified sugars Part 17. Glucal-derived carbene complexes: syhthesis and diastereoselective benzannulation
Doetz, Karl Heinz,Otto, Frank,Nieger, Martin
, p. 77 - 88 (2007/10/03)
The addition of triisopropylsilyl and/or isopropylidene-protected 1-lithio-D-glucals prepared in situ from stannylated precursors 5 and 6 to hexacarbonyl chromium followed by methylation affords D-arabino-hex-1-enopyranosylcarbene complexes 7 and 8. They undergo a diastereoselective benzannulation upon reaction with tolan and 3-hexyne to give polyoxygenated chromans 9 to 12 in good yields and moderate diastereomeric excess values. The confirmation of the glucal moiety in the carbene ligand and in the chroman skeleton is controlled by the nature of the protective groups. 1H-NMR studies and single crystal X-ray analyses indicate a 5H4-conformation of the sugar moiety for the triisopropylsilyl compounds 7, 9a,b, 10a,b and 11 and 4H5-conformation for the isopropylidene derivatives 8 and 12a-c in solution, and further for 8 and 12a in the solid state.
Rapid preparation of variously protected glycals using titanium(III)
Spencer, Roxanne P.,Cavallaro, Cullen L.,Schwartz, Jeffrey
, p. 3987 - 3995 (2007/10/03)
Glycosyl chlorides and bromides can be rapidly converted to glycals in high yield by reaction with (Cp2Ti[III]Cl)2. This reagent tolerates a wide range of common carbohydrate protecting groups, including silyl ethers, acetals, and esters; the methodology provides a general route for the preparation of glycals substituted with both acid- and base-labile functionality. A reaction mechanism is proposed that is based on heteroatom abstraction to give an intermediate glycosyl radical. This radical reacts with a second equivalent of Ti(III) to yield a glycosyltitanium(IV) species. β-Heteroatom elimination from the glycosyltitanium(IV) complex gives the glycal.
Ferrier Rearrangement under Nonacidic Conditions Based on Iodonium-Induced Rearrangements of Allylic n-Pentenyl Esters, n-Pentenyl Glycosides, and Phenyl Thioglycosides
Lopez, J. Cristobal,Gomez, Ana M.,Valverde, Serafin,Fraser-Reid, Bert
, p. 3851 - 3858 (2007/10/02)
Iodonium-promoted rearrangements of easily accessible allylic n-pentenyl esters, n-pentenyl glycosides, or phenyl thioglycosides result in the generation of the allylic oxocarbenium ion intermediate II of the Ferrier rearrangement, I -> II -> IIIa, of glycals leading to 2,3-unsaturated glycosides.Thus the Ferrier rearranmgement can now be carried out under nonacidic conditions, with NIS or iodonium dicollidinium perchlorate as promoter, to afford good yields of disaccharides in which acid-labile functionalities, either in the glycosyl donor or glycosyl acceptor, have been preserved.
