Transition metal catalysed cross-coupling reactions are ubiquitous in organic chemistry providing an impressive technique for C–C bond formation. Whilst many electrophilic partners have been described for these reactions, aryl and vinyl phosphates, phosphonates and phosphonites can offer advantages in terms of preparation, stability and reactivity profile. This critical review summarises the advances made to date utilising P-activated enols in metal-catalysed cross-coupling reactions (97 references).

Transition metal-catalysed cross-coupling reactions of P-activated enols

Total synthesis of (+/-)-magnofargesin.

A total synthesis of the potent, naturally occurring immunomodulators (−)-rapamycin (1) and (−)-27-demethoxyrapamycin (2) has been achieved via a unified, highly convergent synthetic strategy. Both targets were elaborated from common building blocks A−E, the latter available in decagram quantities. Herein we present the construction of the ABC northern perimeters of 1 and 2. The accompanying paper describes the preparation of the southern perimeter DE segment, triene and deprotection model studies, and completion of the synthetic venture. Notable features of the approach include stereoselective σ-bond constructions of trisubstituted olefins and the union of advanced intermediates via efficient dithiane couplings.

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A Unified Total Synthesis of the Immunomodulators (−)-Rapamycin and (−)-27-Demethoxyrapamycin: Construction of the C(21−42) Perimeters

Silica chloride (SiO2Cl)/DMSO, as a heterogeneous system, has been efficiently used for deprotection of thioacetals into aldehydes in dry CH2Cl2 at room temperature. Thioketals without enolizable hydrogens adjacent to a sulfur atom are converted easily to the corresponding ketones in high yields under similar reaction conditions. However, thioketals with enolizable methyl and methylene groups undergo ring-expansion reactions to afford 1,4-dithiepins and 1,4-dithiins in dry CH2Cl2 at room temperature in good yields.

Reactions of Silica Chloride (SiO2Cl)/DMSO, a Heterogeneous System for the Facile Regeneration of Carbonyl Compounds from Thioacetals and Ring-Expansion Annelation of Cyclic Thioacetals

The chemistry of 1,2-carbonyl transposition

Thioacetals are converted into the parent aldehyde or ketone in good yield either by methyl iodide in moist acetone or by methyl fluorosulphonate and water in liquid sulphur dioxide.

Michel Jurion

Papers

Aldehydes and ketones from thioacetals

A new synthesis of Δ2-steroids