A series of unprecedented organoiron complexes of the formal oxidation states −2, 0, +1, +2, and +3 is presented, which are largely devoid of stabilizing ligands and, in part, also electronically unsaturated (14-, 16-, 17- and 18-electron counts). Specifically, it is shown that nucleophiles unable to undergo β-hydride elimination, such as MeLi, PhLi, or PhMgBr, rapidly reduce Fe(3+) to Fe(2+) and then exhaustively alkylate the metal center. The resulting homoleptic organoferrate complexes [(Me4Fe)(MeLi)][Li(OEt2)]2 (3) and [Ph4Fe][Li(Et2O)2][Li(1,4-dioxane)] (5) could be characterized by X-ray crystal structure analysis. However, these exceptionally sensitive compounds turned out to be only moderately nucleophilic, transferring their organic ligands to activated electrophiles only, while being unable to alkylate (hetero)aryl halides unless they are very electron deficient. In striking contrast, Grignard reagents bearing alkyl residues amenable to β-hydride elimination reduce FeXn (n = 2, 3) to clusters of...

Preparation, Structure, and Reactivity of Nonstabilized Organoiron Compounds. Implications for Iron-Catalyzed Cross Coupling Reactions

Macrolactonizations in the Total Synthesis of Natural Products

Recent advances in the preparation and synthetic applications of oxiranes

Cheap, readily available, air stable, nontoxic, and environmentally benign iron salts such as Fe(acac)3 are excellent precatalysts for the cross-coupling of Grignard reagents with alkenyl triflates and acid chlorides. Moreover, it is shown that dichloroarene and -heteroarene derivatives as the substrates can be selectively monoalkylated by this method. All cross-coupling reactions proceed very rapidly under notably mild conditions and turned out to be compatible with a variety of functional groups in both reaction partners. A detailed analysis of the preparative results suggests that iron-catalyzed C−C bond formations can occur via different pathways. Thus, it is likely that reactions of methylmagnesium halides involve iron−ate complexes as the active components, whereas reactions of Grignard reagents with two or more carbon atoms are effected by highly reduced iron-clusters of the formal composition [Fe(MgX)2]n generated in situ. Control experiments using the ate-complex [Me4Fe]Li2 corroborate this inter...

Selective Iron-Catalyzed Cross-Coupling Reactions of Grignard Reagents with Enol Triflates, Acid Chlorides, and Dichloroarenes

Preparation and properties of a novel class of polyhydroxyalkanoate copolymers.

A stereocontrolled total synthesis of optically active (R,R)-phytol

A novel synthetic method for optically active terpenes by the ring-opening reaction of (R)-(+)-β-methyl-β-propiolactone

A three carbon homologation by the ring-opening of β-propiolactones with diorganocuprates

Primary alkyl Grignard reagents react regioselectively with diketene in the presence of cobalt(II) iodide to afford 3-methylenealkanoic acids in good yields. The synthetic utility of this reaction is demonstrated in the syntheses of terpenoids by two methods. Utilizing the isomerization of double bond of 3-methylenealkanoic acids, geranic acid and farnesic acid were obtained in two steps. Another method, the tandem [3,3] sigmatropic rearrangement of the corresponding allylic esters was used for the synthesis of C18-Cecropia juvenile hormone.

Reaction of Diketene with Grignard Reagents in the Presence of Cobalt Catalyst. A Convenient Method for the Synthesis of 3-Methylenealkanoic Acids Leading to Terpenoids

Jasmonoids with cis-2-pentenyl side chain such as cis-jasmone, methyl jasmonate, and jasmolone were easily synthesized from cis-4-heptenoic acid obtained by the ring opening reaction of β-propiolactone with di-cis-butenylcuprate.

Tatsuo Kawara

Papers

A stereocontrolled total synthesis of optically active (R,R)-phytol

A novel synthetic method for optically active terpenes by the ring-opening reaction of (R)-(+)-β-methyl-β-propiolactone

A three carbon homologation by the ring-opening of β-propiolactones with diorganocuprates

Reaction of Diketene with Grignard Reagents in the Presence of Cobalt Catalyst. A Convenient Method for the Synthesis of 3-Methylenealkanoic Acids Leading to Terpenoids

Jasmonoid Synthesis from sci-4-Heptenoic Acid