38231-89-9Relevant academic research and scientific papers
Lewis basic ionic liquid as an efficient and facile catalyst for acetylation of alcohols, phenols, and amines under solvent-free conditions
Ji, Li,Qian, Chao,Chen, Xin-Zhi
, p. 369 - 374 (2013)
The Lewis basic ionic liquid 1,8-diazabicyclo[5.4.0]undec-7-en-8-ium acetate was employed for the acetylation of various phenols, alcohols, and amines in good-to-excellent yields at 50 C under solvent-free conditions in a short time. Compared with existing methods based on conventional catalysts and toxic solvents, the reported method is simple, mild and environmentally viable. Furthermore, the ionic liquid was conveniently separated from the products and easily recycled to catalyze other acetylation reactions with excellent yields. .
Diastereospecific epoxidation and highly regioselective ring-opening of (+)-valienamine: Practical synthesis of (+)-valiolamine
Ji, Li,Zhang, Ding-Feng,Zhao, Qian,Hu, San-Ming,Qian, Chao,Chen, Xin-Zhi
, p. 7031 - 7037 (2013/07/26)
An efficient and practical synthesis of (+)-valiolamine starting from readily available aminocyclitol (+)-valienamine in five steps and up to 80% total yield in gram-scale quantities is reported. Diastereospecific epoxidation by means of substrate directable reaction and regioselective ring-opening of corresponding epoxide are the key reactions in the synthesis, which circumvent laborious purification of products using chromatographical separation. The detailed mechanisms of epoxidation and ring-opening attacked by halide, including the directing and steric hindrance effect, are also discussed.
A C2-symmetric pool based flexible strategy: An enantioconvergent synthesis of (+)-valiolamine and (+)-valienamine
Lo, Hong-Jay,Chen, Cheng-Yih,Zheng, Wei-Lin,Yeh, Shang-Ming,Yan, Tu-Hsin
, p. 2780 - 2785 (2012/07/14)
A new enantioconvergent strategy directed toward the synthesis of glucosidase inhibitors was developed by using a C2-symmetric element within the chiral pool and by applying an iodine-promoted cyclization of an unsaturated carbonimidothioate for the regio- and diastereocontrolled installation of amino and hydroxy units. Not only does this simple flexible strategy provide a convergent concise approach to (+)-valiolamine (1), but it can also be readily adopted for the synthesis of (+)-valienamine (2). Commercially available and cheap C2-symmetric D-tartaric acid served as the chiral building block. Copyright
A concise synthetic approach to (+)-valienamine starting from Garner's aldehyde
Zhou, Bing,Luo, Zhi,Lin, Sui,Li, Yuanchao
supporting information; experimental part, p. 913 - 916 (2012/05/20)
A synthesis of (+)-valienamine was achieved starting from Garner's aldehyde in ten steps and 23% overall yield. A unique feature of the synthetic route is that an acyclic precursor was constructed, using diastereoselective antireductive coupling reaction of alkyne and Garner's aldehyde as the key step, which was then cyclized in an intramolecular aldol reaction to form the valienamine skeleton. Georg Thieme Verlag Stuttgart · New York.
Stereoselective total synthesis of (+)-valienamine and (+)-4-epi- valienamine via a ring-closing enyne metathesis protocol
Radha Krishna, Palakodety,Srinivas Reddy
body text, p. 209 - 212 (2009/06/23)
Stereoselective total synthesis of (+)-valienamine is reported utilizing Sharpless asymmetric dihydroxylation, diastereoselective Carreira alkynylation, and ring-closing enyne metathesis (RCEYM) as key steps from L-serine. A similar strategy is also reported for the first total synthesis of (+)-4-epi- valienamine. Georg Thieme Verlag Stuttgart.
A flexible strategy based on a C2-symmetric pool of chiral substrates: Concise synthesis of (+)-valienamine, key intermediate of (+)- pancratistatin, and conduramines A-1 and E
Chang, Yuan-Kang,Lo, Hong-Jay,Yan, Tu-Hsin
supporting information; experimental part, p. 4278 - 4281 (2010/01/16)
A new strategy invoking a new application of the [3,3] sigmatropic rearrangement of allylic azides and the presence of a C2 symmetry element within a pool of chiral substrates was evolved. Not only does this simple flexible strategy provide a concise approach to (+)-valienamine, but it also can readily be adopted for the synthesis of conduramines A-1 and E and the enantiopure azido carbonate 4, a key intermediate of (+)-pancratistatin.
Carbasaccharides via ring-closing alkene metathesis. A synthesis of (+)- valienamine from D-glucose
Kapferer, Peter,Sarabia, Francisco,Vasella, Andrea
, p. 645 - 656 (2007/10/03)
(+)-Valienamine (16) was prepared in seven steps and in an overall yield of 17% from commercially available 2,3,4,6-tetra-O-benzyl-D-glucopyranose. Stereoselective addition of vinylmagnesium bromide to the 1,3,4,5-tetra-O- benzyl-6,7-dideoxy-L-xylo-hept-6-en-2-ulose (2) gave diene 3 (86%). Ring- closing alkene metathesis of 3 in the presence of 0.15 equiv, of Grubb's catalyst 1 gave the cyclohexene 4 (58%), that was converted into (+)- valienamine (16) in three steps and in 47% yield. Similarly, ring-closing alkene metathesis of the D-mannose-derived diene 20 gave the cyclohexene 21 (89%).
Enantiospecific syntheses of valienamine and 2-epi-valienamine
Shing, Tony K. M.,Li, Tin Y.,Kok, Stanton H.-L
, p. 1941 - 1946 (2007/10/03)
Cyclic sulfite 10, readily available from (-)-quinic acid (3) in 10 steps, was ring opened regio- and stereospecifically with azide anion to give (1S,2R,3R,4R)-1-azido-3,4-di-O-benzyl-5-(benzyloxymethyl)cyclohex-5-ene- 2,3,4-triol (11). Deprotection of 11 afforded, for the first time, 2- epivalienamine (2), which was isolated as penta-N,O-acetyl-2-epi-valienamine (14). The configuration of the free hydroxy group in 11 was inverted by a two-step sequence to give the blocked valienamine 19 that was deprotected to give valienamine (1), isolated as penta-N,O-acetylvalienamine (21). This approach furnished (+)-valienamine (1) in 16 steps (7% overall yield) and recorded the first synthesis of 2-epi-valienamine (2) in 13 steps (11% overall yield).
Total synthesis of (±)- and (+)-valienamine via a strategy derived from new palladium-catalyzed reactions
Trost, Barry M.,Chupak, Louis S.,Luebbers, Thomas
, p. 1732 - 1740 (2007/10/03)
A new strategy toward glycosidase inhibitors, represented by valienamine, which is such an inhibitor itself as well as a critical unit of pseudooligosaccharides that function this way, evolved from two newly developed palladium-catalyzed reactions. The applicability of a palladium(0)-catalyzed net regioselective cis-hydroxyamination derives from the reaction of vinyl epoxides with isocyanates. The utilization of a cocatalyst in this reaction is required in this case and may prove generally useful. A bidentate phosphate proved to be the most effective ligand. The requisite substrate was available via a Diels-Alder protocol and allowed the obtention of (±)-valienamine in only seven steps. The inability to perform the Diels-Alder reaction asymmetrically led to a different asymmetric synthesis of the pivotal epoxide intermediate in enantiomerically pure form, which derived from asymmetric palladium-catalyzed reactions. Using the desymmetrization of meso enedicarboxylates, the net equivalence of an asymmetric cis-hydroxycarboxylation led to the enantiomerically pure desired epoxide. (+)-Valienamine was available in 14 steps by this route.
