共查询到20条相似文献,搜索用时 546 毫秒
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6,6-Diphenylpentafulvenepentacarbonyldiruthenium has been synthesized and its crystal structure determined. 相似文献
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The convergent synthesis of N-Boc-(2R,3R,8R,9R,4E,6E)-3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldecadenoic acid (enantio-N-Boc-ADDA) is reported. Our flexible approach takes advantage of highly efficient non-aldol aldol and cross-metathesis methodologies. 相似文献
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Lyxo-phytosphingosine and erythro-sphingosine have been elaborated from a common intermediate. The key step in the reaction sequence involves stereo- and regiospecific functionalization of an olefin by intramolecular nucleophilic sulfinyl group participation. 相似文献
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The title compounds 1a and 1b have been synthesized in two steps from the saturated pyran-3-ones 2a and 2b , respectively. Upon irradiation (254 nm or 350 nm) in dilute solutions (10?3?10?2M ), compounds 1 undergo a formal [4 + 2] cycloreversion from the excited triplet state to give (2-methylprop-1-enyl)ketene ( 11 ) and either formaldehyde or acetone, ketene 11 being trapped by H2O or MeOH to afford 4-methylpent-3-enoic acid ( 5 ) or its methyl ester 4 in 75–85% isolated yield. In this (monomolecular) photoreaction, heterocycles 1 differ from their alicyclic counterparts, i.e., 4,4-dimethylcyclohex-2-enone ( 10a ) and 4,4,6,6-tetramethylcyclohex-2-enone ( 10b ), as no rearrangement to a 4-oxabicyclo[3.1.0]hexan-2-one occurs. On the other hand, the photochemical behavior of pyranone 1a in bimolecular reactions (cyclodimerization, [2 + 2] cycloaddition to 2,3-dimethylbut-2-ene) resembles that of enone 10a . 相似文献
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The first chiron approach from d-glucose for the total synthesis of (2 S,3 R)-3-hydroxypipecolic acid (-)-1a and (2R,3R)-3-hydroxy-2-hydroxymethylpiperidine (-)-2a is reported. The synthetic pathway involves conversion of d-glucose into 3-azidopentodialdose (5) followed by the Wittig olefination and reduction to give the piperidine ring skeleton (8) with a sugar appendage that on cleavage of an anomeric carbon followed by oxidation gives (-)-1a which on reduction affords (-)-2a. 相似文献
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Amalia M. Estévez Raquel G. Soengas José M. Otero Juan C. Estévez Robert J. Nash Ramón J. Estévez 《Tetrahedron: Asymmetry》2010,21(1):21-26
A divergent synthesis of the two novel polyhydroxylated azepanes (2R,3R,4R,5R,6R)-2-(hydroxymethyl)azepane-3,4,5,6-tetraol and (2R,3R,4R,5R,6S)-2-(hydroxymethyl)azepane-3,4,5,6-tetraol from d-mannose is described. The method involves a Henry reaction between dimethyl-tert-butylsilyl 2,3-O-isopropylidene-α-d-lyxo-pentodialdo-1,4-furanoside and 2-nitroethanol followed by a reductive ring closure of the resulting epimeric nitro aldols. Glycosidase inhibition tests showed that (2R,3R,4R,5R,6S)-2-(hydroxymethyl)azepane-3,4,5,6-tetraol exhibits a weak but selective inhibition against α-l-fucosides. 相似文献
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《Tetrahedron》2017,73(1):39-45
Synthesis of a unique fatty acyl unit to build the N-terminus of callipeltin A and homophymine B is described. Our approach to access (2R, 3R, 4R)-3-hydroxy-2,4,6-trimethylheptanoic acid uses enzymatic hydrolysis for the desymmetrization of achiral acetate, followed by diastereoselective Roush crotylboration and Wittig olefination for the backbone construction. 相似文献
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