Search

Trisubstituted 5-stibano-1H-1,2,3-triazoles were synthesized in moderate to excellent yields by the Cu-catalyzed [3 + 2] cycloaddition of a ethynylstibane with organic azides in the presence of CuBr (5 mol %) under aerobic conditions. The reaction of 5-stibanotriazole with HCl, I2, and NOBF4 afforded 1-benzyl-4-phenyltriazole, 1-benzyl-5-iodo-4-phenyltriazole, and a pentavalent organoantimony compound, respectively.

Siloxy-N-silylketenimines generated in situ from O-silyl cyanohydrins were converted to α-ketoamides by brief exposure to air or oxygen. Oxidation under extremely mild conditions can be explained by assuming the intermediacy of a 3-imino-1,2-dioxetane derivative generated via triplet–singlet intersystem crossing after the reaction of siloxy-N-silylketenimines with triplet oxygen.

A new and efficient high enantioselective method for the synthesis of a wide variety of α-silylimines is developed.

Depending on the base used deprotonation and subsequent benzoylation of α-ureidonitriles proceeds in a highly enantiodivergent manner to give enantiomeric benzoylated products without the need of any chiral catalyst.

α-Chiral nitrile carbanions generated by deprotonation of enantioenriched O-carbamoyl cyanohydrins (I) are trapped in situ with ethyl cyanoformate (II) to give corresponding ester derivatives (III) in high yields and good enantioselectivity.

2-Propylisofagomine (XIV) is prepared via a diastereoselective vinylation of aldehyde (IV), a ring-closing metathesis of the resulting enyne (VI), and a stereoselective hydroboration—oxidation of alkene (XI) as key steps.

A consecutive process is developed for the enantioselective formation of siloxyallenes such as (II) from alkynoylsilanes (I), taking advantage of reduction by a chiral lithium amide followed by stereoselective SE′-type process through the Brook rearrangement of an alkynyl silicate intermediate.

isolation and structure elucidation of six new lupane glucosides as well as the new dammarane glucisode (IV)

Tetra(4-pyridyl)-cavitand 1 and tetrakis(4-hydroxyphenyl)-cavitand 2 self-assemble into a heterodimeric capsule 1·2 via four PhOH⋯pyridyl hydrogen bonds in CDCl3, wherein one molecule of 1,4-disubstituted-benzene as a guest is encapsulated to form a ternary complex, guest@(1·2). The X-ray crystallographic analysis of (methyl p-ethoxybenzoate)@(1·2) confirmed that the methyl ester and ethoxy groups of the encapsulated guest are oriented to the cavity ends of the 1 and 2 units, respectively. The scope and limitation of guest encapsulation in 1·2, including guest-binding selectivity and orientational isomeric selectivity, are described from the viewpoint of size complementarity and CH–π, CH–halogen, and halogen–π interactions between guest and the cavity of 1·2.

The reaction of triarylantimony diacetates (6) with organoboron reagents (9) in the presence of Pd(PPh3)4 led to the formation of cross-coupling products, biaryls (10, 12 and 14–17), in moderate to excellent yields under mild conditions without any base. Similar reaction of 6 with triarylbismuthanes (18) also gave the corresponding cross-coupling products. Single crystal X-ray analysis of tri(p-tolyl)antimony diacetate (6b) and tris(p-trifluoromethylphenyl)antimony diacetate (6e) revealed the geometry of both central antimony atoms being intermediate between trigonal bipyramidal and pentagonal bipyramidal arrangement with intramolecular coordination between the antimony and two carbonyl oxygen atoms with cis orientation.