Highly efficient DABCO-catalyzed [4 + 2] cycloaddition of β,γ-unsaturated α-ketophosphonates or β,γ-unsaturated α-ketoesters with allenic esters gives the corresponding highly functionalized tetrahydropyran and dihydropyran derivatives in good to excellent yields and moderate to good regioselectivities under mild conditions.

A novel PPh3O catalyzed bromophosphonium salt-mediated dibromination of α,β-unsaturated esters and β,γ-unsaturated α-ketoesters has been developed. The products were obtained with good to excellent yields and excellent diastereoselectivities. This dibromination reaction is a good complement to the field of dibromination.

Isothiourea HBTM-2.1 catalyzes the asymmetric Michael addition/lactonization of aryl- and alkenylacetic acids using α-keto-β,γ-unsaturated phosphonates as α,β-unsaturated ester surrogates, giving access to a diverse range of stereodefined lactones or enantioenriched functionalized diesters upon ring-opening.

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 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 difficult to handle and store zinc borohydride, zn(bh4)2, is stabilized by supporting it on polyvinylpyridine. this new mild, efficient, selective, and regenerable polymer supported borohydride reducing agent reduces a variety organic compounds such as, aldehydes, a-b-unsaturated carbonyl compounds, acid chlorides, epoxides, disulfides, as well as reductive acetylation of carbonyl compounds...

Copper-catalyzed borylation of β-trifluoromethyl-α,β-unsaturated ketones was efficiently achieved by means of bis(pinacolato)diboron (B2pin2), affording the enantioenriched products in good yields with high enantioselectivities. CuI and (R,S)-Josiphos consist of the most efficient catalyst system under mild conditions. In the absence of the chiral ligand, the reactions could be performed more e...

The synthesis of γ-amino alcohols 1 is of great interest due to the pharmacology of these compounds and their derivatives. This functionality is found in several antibiotics and other biologically active natural products. Several synthetic methods have been described for the synthesis of γ-amino alcohols 1 from diols, hydroxazols, lactams and lactones, but the more important methods are those w...

Condensation of aromatic aldehydes with benzoyl acetone under specified conditions yieldedtwo series of polycarbonyl compounds in which the keto group is attached to olefinic linkage.Spectral and analytical data revealed the formation of an unsaturated triketone from pyridine-3-carbaldehyde and unsaturated diketone from furfural, salicylaldehyde and 2-hydroxynaphthaldehyde. Analytical, IR, 1H N...

Glaucumolides A (1) and B (2), novel biscembranes composed of an unprecedented α,β-unsaturated ε-lactone, along with the known metabolites ximaolide A (3) and isosarcophytonolide D (4), were isolated from the cultured soft coral Sarcophyton glaucum. The structures of the new metabolites were determined by extensive spectroscopic analyses. Compounds 1 and 2 were shown to exhibit cytotoxicity aga...