TBA[Fe] catalyzes the rearrangement of vinyl and arylcyclopropanes under thermal or photochemical conditions.

The Wittig-typec arbonyl olefination reactionhas no biocatalytic equivalent. To build complex molecular scaffolds, however, CÀCb ond-formingr eactions are pivotal for biobased economy and synthetic biology. The heme-containing E. coli protein YfeX was found to catalyzec arbonyl olefination by reactiono fb enzaldehydew ith ethyl diazoacetateu nder aerobic conditions in the absence of at riphenylphosphine oxophile. The reaction was performed in whole cells and showed ap roduct formation of 440 mg L À1 in 1h.I tw as, moreover,s hown that the reaction could be performed under Wittig-analogue conditions in the presenceo ft riphenylphosphine or triphenylarsine.Although several chemical methods forC ÀCb ond formation are known, biocatalytic alternatives are less developed. Amongst the most established methods are the Grignardr eaction, [1] hydroformylation, [2] andt he Wittig reaction.[3] Ab reakthrough in metal-catalyzed CÀCb ond formation was achieved by the cross-coupling chemistry of Heck, [4] Negishi, [5] and Suzuki, [6] which,t oday,a re standard methods in chemistry laboratories.To construct molecular scaffolds by biocatalytic means, alternative CÀCb ond-forming enzymes are required. Amongst the CÀCb ond-forminge nzymes are aldolases, [7] cyanohydrin lyases, [8] thiamin diphosphate dependent lyases, [9] methyltransferases, [10] and cyclases. [11] We recently reported the catalysis of Friedel-Crafts-type [12] and Prins-ene-typer eactions [11] by am utated squalene-hopenec yclase. The substrate scope, however, of the lyases was very limited, andc yclases have thus far only been shown to catalyze intramolecular reactions.CÀCb ondf ormation reactions are particularly important in synthetic biology,f or which artificial reaction pathways are genetically engineered into organisms and used for the production of industrially relevant molecules.[13] Arnold and co-workers impressively showed the use of heme-containing P450s-which naturally catalyzeh ydroxylation reactions [14,15] -to catalyze carbenoid insertion into C=C [16] and NÀHb onds (Scheme 1).[17] Fasan et al. accomplished these reactions [18,19] and SÀHi nsertions [20] with sperm-whale myoglobin. All these reactions relied on electrophilicc arbenes.Apromising strategyfor the development of novel enzymatic reactions is through analysisofthe transition states of chemical reactions of interest and by comparing these transition states to those existing in biocatalytic reactions. We focused on reactions with nucleophilic carbon atoms,a st hey are required to perform CÀCb ond-forming reactions. The in situ formed iron carbenoid species in the abovementioned hemecatalyzed reactions assembles into as tructure similart ot hat of aC =Pp hosphorane. The carbon atom of these phosphoranes is used in Wittig-type reactions for nucleophilic attack at carbonyl groups and in this way performs carbonyl olefinations.Another example of at ransition state similar to the iron carbenoid species is that formed in the Büchner-Curtius-Schlotterbeck reaction. [21,22] AC ÀCb ond is formed by ...

The Fe–H complex FeH(CO)(NO)(Ph3P)2 catalyzes the stereoselective, regiodivergent hydroboration of internal alkynes using either pinacolborane (HBpin) or bis(pinacolato)diboron (B2pin2) as a boron source.

Tetraaryladamantanes have proven useful as chaperones for the co-crystallization of small molecules that do not readily crystallize by themselves. The co-crystals are often useful for structure elucidation. Usually, the small molecules are encapsulated in the crystal lattice of the aryladamantane that forms during rapid thermal crystallization. Thus far, co-crystallization has been limited to liquids as guest molecules. Here we report the co-crystal structures of phenol, which is solid at room temperature, with both 1,3,5,7-tetrakis(2,4-dimethoxyphenyl)adamantane (TDA) and 1,3,5,7-tetrakis(2,4-diethoxyphenyl)adamantane (TEO). The co-crystals were obtained from solutions in dichloromethane by slow evaporation or diffusion. The implications for generating other co-crystals of two solids are briefly discussed.