Cobalt-Catalyzed Cross-Coupling of α-Bromo Amides with Grignard Reagents.

A cobalt-catalyzed cross-coupling between α-bromo amides and Grignard reagents is disclosed. The reaction is general and allows access to a large variety of α-aryl and ß,γ-unsaturated amides. Some mechanistic investigations have been undertaken to determine the nature of the intermediate species.

Modular Access to Triarylethylene Units from Arylvinyl MIDA Boronates Using a Regioselective Heck Coupling.

A palladium-catalyzed, silver-mediated Heck coupling between arylvinyl MIDA boronate esters and aryl iodides is disclosed. The reaction provides an efficient and modular access to a range of 1,1-diaryl alkenyl MIDA boronates that can be easily transformed into triarylethylene compounds through a Suzuki coupling.

Linchpin dienes: key building-blocks in the synthesis of polyenic frameworks.

A myriad of biologically active products incorporates polyenic frameworks. Among the syntheses developed to access these moieties, metal-catalyzed cross-couplings emerged as reactions of choice especially due to their high stereoselectivity. Particularly, the use of bifunctionalized compounds (linchpin reagents) allows a fast, modular and efficient access to polyenic chains. In this review, we will focus on the preparation of bifunctionalized dienes and on their utilization in the synthesis of polyenes.

Efficient strategy for the synthesis of stereopentad subunits of scytophycin, rifamycin S, and discodermolide.

[reaction: see text] An efficient, simple method has been developed for the stereocontrolled synthesis of polypropionate stereopentads in high enantio- and diastereomeric purities.

Synthesis of stereotriads by oxymercuration of substituted cyclopropylcarbinols.

[structure: see text] Cyclopropylcarbinol derivatives bearing an adjacent methyl-substituted stereocenter and a remote beta-hydroxy group protected as a pivalate underwent anchimerically assisted regio- and diastereoselective oxymercurations, affording after reductive demercuration, an access to stereotriads.

Synthesis of the C1-C12 fragment of fostriecin.

[reaction: see text] The synthesis of the C(1)-C(12) fragment of fostriecin was achieved from (S)-glycidol in 15 steps by using an enantioselective allytitanation reaction and a ring-closure metathesis as the key steps.

A short synthesis of argatroban. a potent selective thrombin inhibitor.

Argatroban was synthesized in seven steps from 4-methylpiperidine. The condensation of (+/-)-trans-benzyl 4-methylpipecolic acid ester with N(alpha)-Boc-N(omega)-nitro-L-arginine led to two diastereomers that were separated. One of them is the precursor of argatroban.

Chemoselective cross-metathesis reaction. Application to the synthesis of the C1-C14 fragment of amphidinol 3.

[reaction: see text] An efficient synthesis of the C1-C14 fragment of amphidinol 3 is described. The synthesis is based on chemoselective cross-metathesis reactions and enantioselective allyltitanations.

Enantioselective allyltitanation. Efficient synthesis of the C1-C14 polyol subunit of amphotericin B.

[structure] An efficient synthesis of the C(1)-C(14) fragment of amphotericin B is described. This synthesis is based on the formation of syn-1,3-diols from enantioselective allyltitanation of unprotected beta-hydroxyaldehydes.

Metallic salt promoted radical cyclization of beta-keto carboxamides and their corresponding beta-enamino carboxamides

Substituted lactams and spirolactams were obtained by Mn(III)-induced radical cyclization of unsaturated beta-keto carboxamides. Treatment of the corresponding tertiary enamines under similar reaction conditions and in the presence of K(2)CO(3) afforded the same cyclized products but with inversion of diastereoselectivity. The oxidation of optically pure secondary enamines leads to diastereomeric spirolactams in an approximately 3:1 ratio.

Desymmetrization of meso-dialdehydes with optically active cyclopentadienyldialkoxyallyltitanium complexes

Optically active cyclopentadienyldialkoxyallyltitanium complexes have been employed for the desymmetrization of meso-dialdehydes. Allylation of these dialdehydes and subsequent oxidation afford chiral lactones with good diastereoselectivity and excellent enantioselectivity.

Enantioselective synthesis of syn- and anti-1,3-diols via allyltitanation of unprotected beta-hydroxyaldehydes

[reaction: see text] syn or anti-1,3-Diols units were synthesized with excellent diastereomeric excess from unprotected chiral beta-hydroxyaldehydes by using an enantioselective allyltitanation.

A short synthesis of troglitazone: an antidiabetic drug for treating insulin resistance.

Troglitazone was obtained in 5 steps from 4-bromo-1,1-dimethoxy-3-methylbut-2-ene with an overall yield of 7.5%. The formation of the chromane ring was achieved by condensing an unsaturated acetal with trimethylhydroquinone in the presence of bis(trifluoromethylsulfonyl)imide.