Catalytic, efficient, and syn-selective construction of deoxypolypropionates and other chiral compounds via Zr-catalyzed asymmetric carboalumination of allyl alcohol

Recent advances in enantioselective copper-catalyzed 1,4-addition

A comprehensive overview of recent literature from 2003 concerning advances in enantioselective copper catalysed 1,4-addition of organometallic reagents to alpha,beta-unsaturated compounds is given in this critical review. About 200 ligands and catalysts are presented, with a focus on stereoselectivities, catalyst loading, ligand structure and substrate scope. A major part is devoted to trapping and tandem reactions and a variety of recent synthetic applications are used to illustrate the practicality and current state of the art of 1,4-addition of organometallic reagents. Finally several mechanistic studies are discussed (162 references).

Efficient and stereoselective synthesis of yellow scale pheromone via alkyne haloboration, Zr-catalyzed asymmetric carboalumination of alkenes (ZACA reaction), and Pd-catalyzed tandem Negishi coupling

A Pd-catalyzed reaction of allylzincs with the 1-octyne bromoboration product gives the desired allyl-alkenyl coupling products in good yields except with H 2CCHCH 2ZnBr. This reaction is suitable for converting an alkyne bromoboration product 3 into 4 with no isomerization or beta-elimination. The Pd-catalyzed isoalkyl-alkenyl coupling of 4 with the isoalkylzinc reagent derived from 2 provides yellow scale pheromone ( 1) of >/=98% isomeric purity in 34% in six steps from TBDPS-protected homoallyl alcohol.

Efficient and selective syntheses of (all-E)- and (6E,10Z)-2'-O-methylmyxalamides D via Pd-catalyzed alkenylation--carbonyl olefination synergy

Highly efficient and selective syntheses of both (all- E) and (6 E,10 Z)-isomers of 2'- O-methylmyxalamide D ( 2 and 3), in which the crucial conjugated pentaene moieties were assembled in > or =98% stereoselectivity through the use of two Pd-catalyzed alkenylation reactions, the Horner-Wadsworth-Emmons (HWE) olefination, and either the Corey-Schlessinger-Mills modified (CSM-modified) Peterson olefination for 2 or the Still-Gennari olefination for 3, are reported. Either 2 or 3 was prepared in 16% yield in seven steps from propargyl alcohol.

Fully reagent-controlled asymmetric synthesis of (-)-spongidepsin via the Zr-catalyzed asymmetric carboalumination of alkenes (ZACA reaction)

The ZACA reaction has been shown to proceed satisfactorily with internally OH-substituted 1-alkenes, provided that the OH group is unprotected and non-allylic. This reaction was used for reagent-controlled asymmetric construction of 3. Allylic alcohol was converted to 2 in seven steps via iterative ZACA processes and simple chromatography. (-)-Spongidepsin (1) was synthesized by using 2 and 3 through application of the esterification-amidation-ring-closing metathesis protocol previously reported.

Deprotonative Metalation Using Ate Compounds: Synergy, Synthesis, and Structure Building

Historically, single-metal organometallic species such as organolithium compounds have been the reagents of choice in synthetic organic chemistry for performing deprotonation reactions. Over the past few years, a complementary new class of metalating agents has started to emerge. Owing to a variable central metal (magnesium, zinc, or aluminum), variable ligands (both in their nature and number), and a variable second metallic center (an alkali metal such as lithium or sodium), "ate" complexes are highly versatile bases that exhibit a synergic chemistry which cannot be replicated by the homometallic magnesium, zinc, or aluminum compounds on their own. Deprotonation accomplished by using these organometallic ate complexes has opened up new perspectives in organic chemistry with unprecedented reactivities and sometimes unusual and unpredictable regioselectivities.

Catalytic asymmetric synthesis of mycocerosic acid

The first catalytic asymmetric total synthesis of mycocerosic acid was achieved via the application of iterative enantioselective 1,4-addition reactions and allows for the efficient construction of 1,3-polymethyl arrays with full stereocontrol; further exemplified by the synthesis of tetramethyl-decanoic acid, a component of the preen-gland wax of the graylag goose, Anser anser.