A synthetic equivalent of the Nazarov reagent, the silyl derivative 2, able to undergo base-catalyzed double Michael addition reactions with α,β-unsaturated carbonyl compounds has been developed. The new reagent satisfactorily reacts with unsaturated indolo[2,3-a]quinolizidine lactams to give pentacyclic yohimbinone-type derivatives.

The first total synthesis of (+)-amabiline, an unsaturated pyrrolizidine alkaloid from Cynoglossum amabile, is reported. This convergent, enantioselective synthesis proceeds in 15 steps (10-step longest linear sequence) in 6.2% overall yield and features novel methodology to construct the unsaturated pyrrolizidine or (-)-supinidine core.

The synthesis of new α,β-unsaturated furanuronic acid derivatives of α-gluco-, β-gluco- and β-manno-chloraloses via a convenient one pot procedure using the Knoevenagel-Doebner reaction approach are described. The dialdofuranose derivatives were reacted with malonic acid under Knoevenagel-Doebner reaction conditions and (E)-α,β-unsaturated furanuronic acid derivatives were obtained.

The 1,4-addition of a monofluoromethyl nucleophile to a variety of alpha,beta-unsaturated compounds has been achieved under mild conditions using either phosphines or potassium carbonate at room temperature. alpha-Substituted fluoro(phenylsulfonyl)methane easily undergoes Michael addition to alpha,beta-unsaturated ketones, esters, nitriles, sulfones, as well as propynoates at room temperature t...

β'-Chloro and β',γ'-unsaturated trichlorotitanium enolates, which were formed in situ by titanium(IV) chloride-mediated ring cleavage of 3,3-dialkylcyclobutanones and 3-[(trimethylsilyl)methyl]cyclobutanones, reacted with enones to give Michael adducts with keeping a labile β'-chloro or β',γ'-unsaturated group.

A little cooperation goes a long way: The cooperative Brønsted/Lewis acid-base supramolecular catalysts formed in situ from simple chiral magnesium(II) binaphtholate aqua complexes promoted the highly enantioselective 1,4-hydrophosphinylation of α,β-unsaturated esters with diaryl phosphine oxides and 1,2-hydrophosphonylation of α,β-unsaturated ketones with dialkyl phosphites (see scheme).

The first organocatalytic double Michael cascade reaction between unsaturated ketones and unsaturated pyrazolones has been developed which provides spiropyrazolone core structures containing two interval or three consecutive stereogenic centers with excellent diastereo- (>20:1) and enantioselectivities (up to 99% ee). Moreover, a pair of enantiomers and can be achieved via different catalysts.

The N-heterocyclic carbene (NHC)-organocatalyzed enantioselective annulation reaction of pyrazolones with α,β-unsaturated aldehydes proceeding via the chiral α,β-unsaturated acyl azolium intermediates under oxidative conditions is presented. The reaction afforded dihydropyranone-fused pyrazoles in moderate to good yields and good er values under operationally simple and base-free conditions.

The feeding of a diet rich in unsaturated fats to rabbits produced no significant alteration of the serum cholesterol level, while the feeding of a diet rich in saturated fats produced an elevation of the serum cholesterol without the development of experimental atherosclerosis. The addition of unsaturated fnts to a diet rich in cholesterol failed to prevent hypercholesterolemia and experimenta...