Horner-Wadsworth-Emmons olefination of nonstabilized phosphonates. A new synthetic approach to β,γ-unsaturated amides

Mn(OAc)3-mediated phosphonation–lactonization of alkenoic acids: synthesis of phosphono-γ-butyrolactones

A new, general method for the synthesis of phosphono-γ-butyrolactones has been achieved through Mn(OAc)₃-mediated radical oxidative phosphonation and lactonization of alkenoic acids withH-phosphonates andH-phosphine oxide.

One-pot synthesis of (E)-α-chloro-α,β-unsaturated esters

Chlorination of a phosphonate anion derived in situ from methyl bis(2,2,2-trifluoroethoxy)phosphonoacetate 2 followed by the addition of aldehydes constitutes a stereoselective single flask procedure for the preparation of E-configured α-chloro-α,β-unsaturated esters.

Sequential Reactions Promoted by Manganese: Completely Stereoselective Synthesis of (E)-α,β-Unsaturated Amides, Ketones, Aldehydes, and Carboxylic Acids

A complete E-selective synthesis of alpha,beta-unsaturated amides through a sequential reaction of a range of dichloroamides with a variety of aldehydes promoted by Rieke manganese (Mn*) is reported. A mechanism based on a sequential aldol-type reaction and a completely stereoselective beta-elimination is proposed to explain these results. The unsaturated amides obtained are readily and efficiently transformed into alpha,beta-unsaturated ketones, aldehydes, or carboxylic acids without loss of the diastereoisomeric purity of the C-C double bond.

Total synthesis of (-)-senepodine G and (-)-cermizine C

An efficient, stereospecific synthesis of the alkaloids senepodine G (2) and cermizine C (1) has been completed using the BF3.Et2O-promoted stereospecific addition of Me2CuLi to alpha,beta-unsaturated lactam 6 to provide lactam 3, the addition of MeMgBr followed by HCl to convert 3 to senepodine G (2) (six steps, 40% overall yield), and the stereospecific NaBH4 reduction of 2 to give cermizine C (1) (seven steps, 40% overall yield).

SM. Structural determinants of opioid activity in derivatives of 14-aminomorphinones: effects of changes to the chain linking of the C14-amino group to the aryl ring

The 14-aminodihydromorphinone and codeinone series of opioid ligands have produced a number of ligands of substantial interest. To investigate the importance of the 14-substituent, a series of analogues in which the side chain length is varied and the amide and alkene functions are reduced have been prepared. Binding affinity, particularly at the mu-opioid receptor (MOR), was largely determined by the aromatic group of the side chain. In the [35S]GTPgammaS functional assay, the ligands having a three-carbon side chain were more potent antagonists than their longer chain counterparts, while shorter, two-carbon chain analogues were of higher MOR efficacy, an effect that was confirmed in vivo. Wash-resistant binding was observed within this series and appeared to be unrelated to side-chain length.

Novel route to 5-position vinyl derivatives of thiolactomycin: Olefination vs. deformylation

Vinyl and diene derivatives of thiolactomycin have been prepared via Horner-Wadsworth-Emmons olefination from protected 5-formyl-3,5-dimethylthiotetronic acid. Several 4-position protecting groups and a variety of phosphonates were evaluated, with MOM protection and beta-ketophosphonates yielding the highest ratio of desired product to deformylated product.

Synthesis of (E)-alpha,beta-unsaturated amides with high selectivity by using samarium diiodide

Stereoselective beta-elimination of 2-chloro-3-hydroxyamides 1 is achieved by using samarium diiodide to yield alpha,beta-unsaturated amides 2, in which the C=C bond is di- tri-, or tetrasubstituted. The starting compounds 1 are easily prepared by reaction of the corresponding lithium enolates of alpha-chloroamides with aldehydes or ketones at - 78 degrees C. The influence of the reaction conditions and the structure of the starting compounds on the stereoselectivity of the beta-elimination reaction is also discussed.