14161-72-9

Tertiary and benzyl alcohols with a γ-trialkyltin group from cyclopropanes stereospecifically on treatment with acid, with inversion of configuration at both carbon atoms.

A variety of highly diastereo- and enantiomerically enriched arylcyclopropanes is obtained through the asymmetric rhodium-catalyzed arylation reaction of achiral nonfunctionalized cyclopropene derivatives with commercially available aryl boronic acids in the presence of (R,S)-Josiphos.

The modular synthesis of a variety of trans 1,2-disubstituted cyclopropanes in a safe and user-friendly one-pot iron-catalyzed cyclopropanation reaction is described. Easily synthesized N-nosylhydrazones are used as diazo precursors, allowing the in situ generation of electron-rich diazo compounds under mild reaction conditions and their direct participation in the cyclopropanation reaction.

The enantioselective synthesis of cyclopropylzinc reagents has been achieved via a copper-catalyzed carbozincation of 3,3-disubstituted cyclopropenes with diorganozinc reagents. The obtained organozinc compounds can be easily functionalized with a broad range of electrophiles, including palladium-catalyzed cross-couplings, affording highly substituted cyclopropanes. The operationally simple procedure using very low quantities of a commercially available and inexpensive copper catalyst provides a new tool for the synthesis of highly enantioenriched cyclopropanes as single diastereoisomers.

A novel Cu-catalyzed diastereo- and enantioselective desymmetrization of cyclopropenes to afford nonracemic cyclopropylboronates is described. Trapping the cyclopropylcopper intermediate with electrophilic amines allows for the synthesis of cyclopropylaminoboronic esters and demonstrates the potential of the approach for the synthesis of functionalized cyclopropanes.

The Simmons-Smith reaction of zinc carbenoids with alkenes is a powerful method to access cyclopropanes containing various substitution patterns. This work exploits the high reactivity of aryldiazomethanes toward zinc halides to generate aryl-substituted carbenoids catalytically. These carbenoids are able to cyclopropanate various alkenes diastereoselectively, including unfunctionalized substrates such as styrenes. The zinc catalyst can be modified to tolerate the use of free allylic alcohols.

We report the use of three enantiomerically pure and electronically tuned ruthenium carbonyl porphyrin catalysts for the asymmetric cyclopropanation and epoxidation of a variety of olefinic substrates. The D4-symmetric ligands carry a methoxy, a methyl or a trifluoromethyl group at the 10-position of each of the 9-[anti-(1,2,3,4,5,6,7,8-octahydro-1,4:5,8-dimethanoanthracene)]-substituents at the meso-positions of the porphyrin. Introduction of a CF 3-substituent in this remote position resulted in greatly improved catalyst stability, and turnover numbers of up to 7500 were achieved for cyclopropanation, and up to 14200 for epoxidation, with ee values typically >90% and ≈80%, respectively. In one example, the axial CO ligand at the ruthenium was exchanged for PF3, resulting in the first chiral ruthenium porphyrin with a PF3 ligand reported to date. In cyclopropanations with ethyl diazoacetate, the latter catalyst performed exceedingly well, and gave a 95% ee in the case of 1,1-diphenylethylene as substrate.

(Equation presented) A user-friendly, one-pot process for catalytic cyclopropanation of alkenes from tosylhydrazones is described. The cyclopropanation of N-vinylphthalimide provides a new route to 2-arylcyclopropylamines, and this is exemplified in the efficient synthesis of the HIV-1 reverse transcriptase inhibitor 6.

Pyrolysis of the relatively stable, solid complexes of cyclomaltoheptaose (β-cyclodextrin) with phenyldiazomethane, 1-diazo-1-phenylethane, and diazo(diphenyl)methane results in degradation of the labile guests.The host matrix exerts "reaction-vessel" and "shape-selectivity" effects upon the reaction pathways of the guests and derivatives.The carbene insertion reaction with the β-cyclodextrin hydroxyl groups is regioselective.

Phenylmethyldiazirine forms a stable, solid complex with β-cyclodextrin.The diazirine was decomposed by pyrolysis or irradiation of the complex, and the reaction products were analyzed.The major volatile products consist of the isomeric 1,2-diphenyl-1-methylcyclopropanes.Under photolytic conditions a significant amount of styrene also is formed.The selectivity for trans isomer formation is 10 times greater from the CD complex than from the neat state.Carbene insertion products with β-cyclodextrin are formed under both reaction conditions.The product distributions are explained by cage and shape-selective effects exerted by β-cyclodextrin.

Product analysis and deuterium labelling experiments suggest that the critical intermediate in the reduction of ArCOCH2R with Zn/HCl is a zinc-carbene; this may be protonated to give ArCH2CH2R, converted into ArCH=CHR by rearrangement, deprotonated to give a vinyl-zinc species, or captured by an alkene to give a cyclopropane.

γ-Stannyl tertiary alcohols and γ-stannyl benzyl alcohols form cyclopropanes strereospecifically on treatment with acid, with inversion of configugation at both carbon atoms.

A series of gem-dichlorocyclopropyl and cyclopropyl analogs of stilbene congeners was synthesized and examined for estrogenic and antiestrogenic activity using the uterotropic assay in the immature mouse. The relative receptor affinity in vitro was determ