Intramolecular 1,3-Dipolar Cycloaddition of Transient Enantiomerically Pure Oxaalkenyl Nitrones

Asymmetric 1,3-Dipolar Cycloaddition Reactions

“…Several groups have reported intramolecular reactions of 5-alkenylnitrones in which the chiral center is located on a carbon atom in the alkene-nitrone link, leading to 3-oxa-2-azabicyclo[3.3.0]octanes and heteroanalogues. 115,[117][118][119][120][121][122][123][124][125] Aurich et al have made extensive studies on reactions involving alkenylnitrones 96, formed in situ from 5-alkenylaldehydes 95. 117,119,121,122,124 The substituent located vicinal to the nitrone carbon atom, directing the facial selectivity of the reaction is most frequently alkyl, benzyl, or phenyl, but occasionally other oxygen or nitrogen substituents have been applied.…”

Construction of the 11-oxabicyclo[6.2.1]undecane core of the cladiellins by a novel rearrangement reaction

“…6 Ring opening of the lactone 1 was effected using a sub-stoichiometric amount of 10-camphorsulfonic acid (CSA) in a mixture of nbutanol and toluene at reflux, 7 and the resulting diester was then converted into the allyl ether 2 by silver(I) oxide promoted alkylation of the free hydroxy group with excess allyl bromide. 8 Saponification of the diester 2 and treatment of the resulting diacid with acetic anhydride provided the substituted glutaric anhydride 3. Reaction of the cyclic anhydride 3 with a large excess of diazomethane resulted in contrasteric opening of the ring to afford the diazoketone 4 in reasonable yield, without formation of the other possible regioisomeric diazoketone product.…”

Micellar and structural stability of nanoscale amphiphilic polymers: Implications for anti-atherosclerotic bioactivity

“…Ag 2 O served as both catalyst for ether formation [28] and oxidizing reagent [30] in the first step. The successful synthesis was indicated by the disappearance of the methine backbone peak (Figure S1).…”

“…Following a modified published procedure [28], a solution of dibenzyl L-tartrate (DBT, 661 mg, 2.00 mmol) and bromododecane (0.99 mL, 4.00 mmol) were dissolved in 10 mL anhydrous diethyl ether. Upon complete dissolution, silver (I) oxide (Ag 2 O, 1.07 g, 4.60 mmol) was added and the reaction was refluxed in the dark at 47 °C for 72 h. The reaction mixture was filtered through a celite column and washed repeatedly with diethyl ether (3× 10 mL).…”