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
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.
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.
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.
