13. Triethylborane (Et3B-O2)
T. Yoshimitsu, Encyclopedia of Reagents for Organic Synthesis, Paquette, L. A.; Fuchs, P. L.; Wipf, P.; Crich, D. Eds.: John Wiley&Sons (2005).
12. Radical α-functionalization of ethers
T. Yoshimitsu, Handbook of C-H Transformations, G. Dyker, Ed., Wiley-VCH, vol. 2, pp. 377-385 (2005).
11. Radical α-C-H hydroxyalkylation of ethers and acetal
T. Yoshimitsu, Y. Arano, H. Nagaoka, J. Org. Chem., 70, 2342-2345 (2005).
10. Radical hydroxyalkylation of C-H bond adjacent to nitrogen of tertiary amides, ureas, and amines
T. Yoshimitsu, Y. Arano, H. Nagaoka, J. Am. Chem. Soc., 127, 11610-11611 (2005).
9. Development of useful reactions involving tandem cyclizations based on the novel reactivities of allenic compounds
H. Ohno, Chem. Pharm. Bull., 53(10), 1211-1226 (2005).
8. Development of useful reactions based on the novel reactivities of allenic compounds and their application to tandem cyclizations
H. Ohno, Yakugaku Zasshi, 125(12), 899-925 (2005).
7. Total Synthesis of Murisolins and Evaluation of Tumor Growth-Inhibitory Activity
N. Maezaki, H. Tominaga, N. Kojima, M. Yanai, D. Urabe, R. Ueki, T. Tanaka, T. Yamori, Chem. Eur. J., 11, 6237-6245 (2005).
Abstract:Convergent total synthesis of murisolin 1, natural 16,19-cis-murisolin 2 and unnatural 16,19-cis-murisolin 3 was accomplished by asymmetric alkynylation of α-tetrahydrofuranic aldehyde with diyne and Sonogashira coupling with γ-lactone segment as the key steps. Stereoisomers of the α-tetrahydrofuranic aldehyde were synthesized with high optical purity and the asymmetic alkynylation of them with 1,6-heptadiyne proceeded in good yield and with high diastereoselectivity. The cell growth inhibition profile and the COMPARE analysis of the synthetic 1-3 were also investigated.
6. Diastereoselective Ni(0)-Catalyzed Carbocyclization to Chiral Vinylic Sulfoxide
N. Maezaki, H. Sawamoto, H. Ishihara, T. Tanaka, Chem. Commun., 3992-3994 (2005).
Abstract:Diastereoselective Ni(0)-catalyzed carbocyclization of enone to chiral vinylic sulfoxide was accomplished.
5. Thermal Intramolecular [2 + 2] Cycloaddition of Allenenes and Allenynes: Diastereoselective Approach to Bicyclic Heterocycles
H. Ohno, T. Mizutani, Y. Kadoh, K. Miyamura, T. Tanaka, Angew. Chem., Int. Ed., 44, 5113-5115 (2005); Angew. Chem., 117, 5243-5245 (2005).
Abstract:A novel entry to bicyclo[4.2.0]octane derivatives has been developed by using [2 + 2] cycloaddition of allenenes or allenynes. Thermal [2 + 2] cycloaddition of simple allenes with an additional multiple bond led to direct and regioselective formation of distal adducts, bicyclo[4.2.0]octane derivatives in good to excellent yields.
4. Palladium-Catalyzed Tandem Cyclization of Bromoenynes through Aromatic C-H Bond Functionalization
H. Ohno, M. Yamamoto, M. Iuchi, T. Tanaka, Angew. Chem., Int. Ed., 44, 5103-5106 (2005); Angew. Chem., 117, 5233-5236 (2005).
Abstract:Tandem cyclization of 1-aryl-4-aza-2-bromo-1-alken-6-ynes with catalytic Pd(OAc)2 and cesium carbonate in EtOH led to direct construction of tri- or tetracyclic heterocycles, through intramolecular carbopalladation and aromatic C-H bond functionalization.
3. Chemo- and Stereoselectivity in Titanium-Mediated Regioselective Ring-Opening Reaction of Epoxides at the More Substituted Carbon
T. Tanaka, K. Hiramatsu, Y. Kobayashi, H. Ohno, Tetrahedron, 61, 6726-6742 (2005).
Abstract:Chemo- and stereoselectivity in the ring-opening reaction of epoxides with a reagent prepared from allylmagnesium halide and chlorotitanium triphenoxide is described. It has been proven that the allylating reagent can also be used for the reaction of epoxides bearing a tert-butyl ester, amide, or acetal moiety, and that the epoxide cleavage regioselectively takes place at the more substituted carbon in all cases. Interestingly, while the reaction of acyclic 2,2,3-trialkyl epoxides or 3,3-disubstituted 2,3-epoxy alcohol derivatives with the allyltitanium reagent yielded the allylated products as an almost 1:1 diastereomixture, the ring-opening reaction of 2-substituted 2,3-epoxy alcohol derivatives stereospecifically proceeded through the anti pathway. The latter reaction is extremely useful for asymmetric construction of quaternary carbon centers.
2. Palladium(0)-Catalyzed Tandem Cyclization of Allenenes: Direct Construction of Tricyclic Heterocycles through Aromatic C-H Activation
H. Ohno, K. Miyamura, T. Mizutani, Y. Kadoh, Y. Takeoka, H. Hamaguchi, T. Tanaka, Chem. Eur. J., 11, 3728-3741 (2005).
Abstract:Palladium(0)-catalyzed tandem cyclization of allenenes is described. Treatment of allenenes with an aryl halide, potassium carbonate, and catalytic [Pd(PPh3)4] in dioxane afforded tri- or tetracyclic heterocycles in moderate to good yields through insertion of arylpalladium(II) halide to the allenic moiety, intramolecular carbopalladation, and aromatic C-H bond activation. The substituent on the olefin terminus has proven to be essential for the success of the tandem cyclization. The reaction with heterocyclic aryl halides such as iodopyrazine or 4-bromo-1-methylindole afforded tri- or tetracyclic heteroaromatic products in good yields.
1. Bromoallenes as Allyl Dication Equivalents in the Absence of Palladium(0): Synthesis of Bicyclic Sulfamides by Tandem Cyclization of Bromoallenes
H. Hamaguchi, S. Kosaka, H. Ohno, T. Tanaka, Angew. Chem., Int. Ed., 44, 1513-1517 (2005); Angew. Chem., 117, 1537-1541 (2005).
Abstract:A highly regioselective synthesis of cyclic sulfamides containing a bicyclo[3.3.0]octane skeleton has been developed. The first intramolecular nucleophilic attack of the internal sulfamide nitrogen atom takes place at the central carbon atom of the allenic moiety, and is followed by a second intramolecular nucleophilic addition of the terminal sulfamide nitrogen atom to afford the bicyclic sulfamide.