Palladium-catalyzed allylic oxidation of 1-(p-toluenesulfonyl)-2-propene and 1-(trimethylsilyl)-1-(p-toluenesulfonyl)-2-propene

The course of palladium-catalyzed oxidation of a terminal alkene by t-BuOOH or by O₂/H₂O is greatly modified when the allylic carbon bears a p-toluenesulfonyl substituent, and allylic oxidation results. Mechanistic explanations of this observation are proposed.     

Reaction of 6-phenyl-2-(p-toluenesulfonyl)-3(2H)pyridazinone with grignard reagents

6-Phenyl-2-(p-toluenesulfonyl)-3(2H)pyridazinone (I) reacted with Grignard reagents to give 5-substituted 4,5-dihydro-3(2H)pyridazinones II and two types of dihydropyridazines, III and IV. The ratio of II, III, and IV was sensitively dependent on the reaction conditions. Further, by quenching the reaction mixture with alcohol, the ring-opened product VII was mainly isolated.     

New route to (3RS) (5R) (5-2H)- and (3RS) (5S) (5-2H)-mevalonolactones

The synthesis of mevalonolactone stereospecifically labeled at carbon 5 is described combining chemical reactions with an enzymatic reduction step.     

Morita-Baylis-Hillman reaction and cyclization of 1-(p-toluenesulfonyl)-1,3-butadiene with aldimines

[reaction: see text] Aldimines 2 underwent Morita-Baylis-Hillman reaction with 1-(p-toluenesulfonyl)-1,3-butadiene (3) in the presence of 3-hydroxyquinuclidine (HQD) to afford adducts 4. The E-isomers of the products cyclized to the corresponding functionalized piperidines 8 under base-catalyzed conditions. Simultaneous equilibration of (E)-4 and (Z)-4 was effected by photoisomerization to improve the efficiency of the cyclization.     

Proposed fluorination mechanism of CB(5)H(6)(-) and CB(9)H(10)(-) with HF. Evidence of kinetic control in the formation of 2-CB(5)H(5)F(-) and 6-CB(9)H(9)F(-)

Two pathways have been considered in the fluorination of CB(5)H(6)(-) and CB(9)H(10)(-) by HF. In the ionic HF fluorination pathway, the monocarborane anion cage is first protonated in a BBB face followed by H(2) elimination and fluoride anion addition. In the covalent HF fluorination pathway, HF is first coordinated through hydrogen to the BBB face. Next, the fluorine can add to either an axial or equatorial boron atom which opens the cage to a nido structure with an endo fluoride substituent. Endo to exo rearrangement occurs with a small activation barrier followed by H(2) elimination. In both pathways, fluorination at the equatorial boron position is predicted to have smaller activation barriers even though substitution at the axial position leads to the more stable products.     

Anion photoelectron spectroscopy of C(5)H(-)

Anion photoelectron spectroscopy is performed on the C(5)H(-) species. Analogous to C(3)H(-) and C(3)D(-), photodetachment transitions are observed from multiple, energetically close-lying isomers of the anion. A linear and a cyclic structure are found to have electron binding energies of 2.421+/-0.019 eV and 2.857+/-0.028 eV, respectively. A cyclic excited state is also found to be 1.136 eV above the linear (2)Pi C(5)H ground state. Based on our assignments of the observed transitions and previous calculations on the energetics of neutral C(5)H isomers, the cyclic (1)A(1) anion state is found to lie 0.163 eV below the (3)A linear anion.     

Crystal Structure of 5-(l-Menthyloxy)-3-Bromo-4-(R)-(+)-Methylbenzylamino-2(5H)-Furanone

１ＩＮＴＲＯＤＵＣＴＩＯＮＳｅｖｅｒａｌｉｍｐｏｒｔａｎｔａｐｐｒｏａｃｈｅｓｔｏｔｈｅｓｙｎｔｈｅｓｉｓａｎｄｐｒｏｐｅｒｔｉｅｓｏｆｃｈｉｒａｌγ ａｌｋｙｌｏｘｙｂｕｔｅｎｏｌｉｄｅｓｈａｖｅａｔｒａｃｔｅｄｍｕｃｈａｔｅｎｔｉｏｎｏｗｉｎｇｔ...     

1,3-Dipolar Cycloaddition of Substituted Benzonitrile Oxide to 5-(R)-(l-Menthyloxy)-2(5H)-furanone

Isoxazoline compounds as key intermediates for construction of natural products have been developed very fast as an hot area in organic synthesis1. 5-(R)-(l-menthyloxy)- 2(5H)-furanone as a valuable chiral synthon has been recently studied for its high stereoselectivity in many reactions2. In this paper, we focused on its reactivity and regioselectivity of the 1,3-dipolar cycloaddition with the substituted benzonitrile oxide3 and several isoxazoline compounds were obtained and characterized…     

Crystal Structure of 5-(l-Menthyloxy)-3-Chloro-4-Pyrrolidinyl-2(5H)-Furanone

１ＩＮＴＲＯＤＵＣＴＩＯＮＯｗｉｎｇｔｏｔｈｅｉｒｗｉｄｅｏｃｃｕｒｅｎｃｅｉｎａｖａｒｉｅｔｙｏｆｂｉｏｌｏｇｉｃａｌｙａｃｔｉｖｅｎａｔｕｒａｌｐｒｏｄｕｃｔｓａｎｄｔｈｅｉｒｕｔｉｌｉｔｙａｓｖａｌｕａｂｌｅｓｙｎｔｈｅｔｉｃｉｎｔｅｒｍｅｄｉ...