118574-88-2Relevant academic research and scientific papers
Total synthesis of (+)-conagenin
Chakraborty, Tushar Kanti,Sudhakar, Gangarajula
, p. 5847 - 5849 (2007/10/03)
The total synthesis of the immunomodulator, (+)-conagenin was achieved using, as a key step, a method developed by us for the synthesis of 2-methyl-1,3-diols via Ti(III)-mediated diastereo- and regioselective opening of trisubstituted 2,3-epoxy alcohols,
Design of optically active hydroxamic acids as ligands in vanadium- catalyzed asymmetric epoxidation
Hoshino, Yujiro,Murase, Noriaki,Oishi, Masataka,Yamamoto, Hisashi
, p. 1653 - 1658 (2007/10/03)
New optically active hydroxamic acids bearing a 1,1'-binaphthyl group were prepared as ligands in a vanadium-catalyzed asymmetric epoxidation. The feature of these hydroxamic acids is a sterically hindered ligand. The asymmetric epoxidation with good selectivity and reactivity can be established by using VO(O-i-Pr)3 (5 mol%) and a small excess amount of ligand (7.5 mol%) with triphenylmethyl hydroperoxide (TrOOH) in toluene at - 20 °C. Disubstituted allyl alcohols were epoxidized more rapidly than mono- or tri-substituted allyl alcohols, and were obtained in good to high enantioselectivities (48 - 94%ee). The transition state based on X-ray crystal structure of 1e is discussed.
Synthetic studies toward potent cytotoxic agent amphidinolide B : Synthesis of the entire C14-C26 moiety of the top half
Chakraborty, Tushar K.,Thippeswamy, Devasamudram,Suresh, Vayalakkada R.,Jayaprakash, Sarva
, p. 563 - 564 (2007/10/03)
Regioselective hydroboration of a 4-methyl-2-alkene, oxidation of the resulting mixture of isomeric alcohols, and finally diastereoselective reduction of the ketone are the key steps in the stereoselective synthesis of C19-C26 fragment of amphidinolide B
Total synthesis of (+)-tautomycin
Ichikawa, Yoshiyasu,Tsuboi, Katsunori,Jiang, Yimin,Naganawa, Atsushi,Isobe, Minoru
, p. 7101 - 7104 (2007/10/02)
Tautomycin molecule was disconnected into 3 retrosynthetic segments, A, B, and C, each of which was synthesized in optically active form. First coupling between Segments B and C was achieved between an epoxide and a sulfone carbanion in the presence of BF
HIGHLY ANTISELECTIVE SN2' ADDITIONS OF LiMe2Cu TO CHIRAL ACYCLIC VINYLOXIRANES
Marshall, James A.,Trometer, Joseph D.,Blough, Bruce E.,Crute, Thomas D.
, p. 913 - 916 (2007/10/02)
Additions of LiMe2Cu to the trans and cis-Z vinyloxiranes 8 and 10 proceed with virtually 100percent anti diastereoface selectivity to afford the syn-Z diol 12 and the anti-E diol 13 as the major products.
Stereochemistry of SN2' Additions to Acyclic Vinyloxiranes
Marshall, James A.,Trometer, Joseph D.,Blough, Bruce E.,Crute, Thomas D.
, p. 4274 - 4282 (2007/10/02)
The isomeric trans-(E)-, trans-(Z)-, cis-(E)-, and cis-(Z)-vinyloxiranes 7,9,17 and 19 were prepared from 2-(benzyloxy)ethanol by sequential Swern-Wittig or Swern-Horner-Emmons propionate condensation, DIBAH reduction, Sharpless epoxidation, Swern oxidation, Wittig or Horner-Emmons acetate condensation, and a second DIBAH reduction.Addition of lithium dimethylcuprate and lithium methylcyanocuprate to these epoxides in THF-eather at -20 to 0 deg C afforded the allylic alcohols 22,25, ent-23, and ent-22 as the major products.These products are formed by anti addition to the lower energy conformer (s-trans for 7,17, and 19 and s-cis for 9) of the respective vinyloxirane.The conformational preferences of transition-state-like geometries of the vinyl-oxiranes, calculated with the aid of Still's MACROMODEL program, were in agreement with the observed trends.
AN ENANTIOSELECTIVE SYNTHESIS OF THE CARZINOPHILIN DEGRADATION PRODUCT (2S,3S) 4-AMINO-2,3-DIHYDROXY-3-METHYLBUTYRIC ACID
Garner, Philip,Park, Jung Min,Rotello, Vicent
, p. 3299 - 3302 (2007/10/02)
An efficient, enantioselective synthesis of (2S,3S) 4-amino-2,3-dihydroxy-3-methylbutyric acid (1) is described.The sequence includes the direct use of azide to selectively open a secondary epoxy alcohol formed under Payne rearrangement conditions.
