460752-17-4Relevant academic research and scientific papers
Stereoselective synthesis of E,Z-configured 1,3-dienes by ring-closing metathesis. Application to the total synthesis of lactimidomycin
Gallenkamp, Daniel,Fuerstner, Alois
, p. 9232 - 9235 (2011/08/06)
Strategic positioning of a silyl group on the diene unit of a diene-ene substrate allows rigorous regio- and stereocontrol to be exerted during metathesis-based macrocyclization reactions. The versatility of this concise approach to E,Z-configured 1,3-die
Sequential Ru-Pd catalysis: A two-catalyst one-pot protocol for the synthesis of N- and O-heterocycles
Trost, Barry M.,Machacek, Michelle R.,Faulk, Brian D.
, p. 6745 - 6754 (2007/10/03)
An atom economic, selective, and highly practical two-metal one-pot synthesis of heterocycles has been developed that efficiently affords enantio- and diastereopure N- and O-heterocyclic products. Furthermore, use of a chiral catalyst in the two-metal procedure allows formation of all possible diastereomers, even those that are traditionally difficult to access via cyclization routes due to thermodynamics. Interestingly, the nature of the enantiodiscriminating event differs between the use of amine versus alcohol nucleophiles. The method also affords heterocyclic products that are synthetically useful intermediates. Through the Z-vinylsilane a variety of stereodefined trisubstituted olefin products can be accessed including several all-carbon motifs. Finally, the utility of these heterocyclic products in total synthesis is demonstrated through concise syntheses of a kainoid intermediate, a constituent of oil of rose, and the ring B portion of bryostatin, a potent chemotherapeutic.
1,2-Silyl-migrative cyclization of vinylsilanes bearing a hydroxy group: Stereoselective synthesis of multisubstituted tetrahydropyrans and tetrahydrofurans
Miura, Katsukiyo,Hondo, Takeshi,Okajima, Shigeo,Nakagawa, Takahiro,Takahashi, Tatsuyuki,Hosomi, Akira
, p. 6082 - 6090 (2007/10/03)
Acid-catalyzed intramolecular addition of a hydroxy group to α-alkylated vinylsilanes has been studied. Treatment of (Z)-5-alkyl-5-silyl-4-penten-1-ols 1 (R = alkyl) with 5 mol % TiCl4 in CHCl3 gave trans-2-alkyl-3-silyltetrahydropyrans 2 exclusively (trans/cis = > 99/1 to 97/3). The cyclization efficiency and rate strongly depended on the geometry of the C-C double bond and the silyl group. The use of (E)-vinylsilanes resulted in lower yields with poor cis-selectivity. In the cyclization of (Z)-1 (R = Bu), the silyl group used, the reaction time, and the yield of 2 were as follows: SiMe2Ph, 9.5 h, 75%; SiMe3, 7.5 h, 66%; SiMePh2, 24 h, 58%; SiMe2-t-Bu, 0.75 h, 85%; SiMe2Bn, 1.5 h, 78%. This 1,2-silyl-migrative cyclization could be applied to stereoselective synthesis of trisubstituted tetrahydropyrans. The acid-catalyzed reaction of 1-, 2-, or 3-substituted (Z)-5-silyl-4-nonen-1-ols 8 gave r-2,t-3,c-6-, r-2,t-3,t-5-, or r-2,t-3,c-4-trisubstituted tetrahydropyrans with high diastereo-selectivity, respectively. (Z)-4-Alkyl-4-silyl-3-buten-1-ols 5 as well as 1 underwent the 1,2-silylmigrative cyclization to give 2-alkyl-3-silyltetrahydrofurans 6 with high trans-selectivity. This silicon-directed cyclization was also available for the stereoselective synthesis of tri- and tetrasubstituted tetrahydrofurans.
