Uncovering the psychoactivity of a cannabinoid from liverworts associated with a legal high.

Phytochemical studies on the liverwort Radula genus have previously identified the bibenzyl (-)-cis-perrottetinene (cis-PET), which structurally resembles (-)-Δ9-trans-tetrahydrocannabinol (Δ9-trans-THC) from Cannabis sativa L. Radula preparations are sold as cannabinoid-like legal high on the internet, even though pharmacological data are lacking. Herein, we describe a versatile total synthesis of (-)-cis-PET and its (-)-trans diastereoisomer and demonstrate that both molecules readily penetrate the brain and induce hypothermia, catalepsy, hypolocomotion, and analgesia in a CB1 receptor-dependent manner in mice. The natural product (-)-cis-PET was profiled on major brain receptors, showing a selective cannabinoid pharmacology. This study also uncovers pharmacological differences between Δ9-THC and PET diastereoisomers. Most notably, (-)-cis-PET and (-)-trans-PET significantly reduced basal brain prostaglandin levels associated with Δ9-trans-THC side effects in a CB1 receptor-dependent manner, thus mimicking the action of the endocannabinoid 2-arachidonoyl glycerol. Therefore, the natural product (-)-cis-PET is a psychoactive cannabinoid from bryophytes, illustrating the existence of convergent evolution of bioactive cannabinoids in the plant kingdom. Our findings may have implications for bioprospecting and drug discovery and provide a molecular rationale for the reported effects upon consumption of certain Radula preparations as moderately active legal highs.

Stereochemistry and biological activity of chlorinated lipids: a study of danicalipin A and selected diastereomers.

The syntheses of (+)-16-epi- and (+)-11,15-di-epi-danicalipin A (2 and 3) are reported. The conformations of the parent diols 5 and 6 as well as the corresponding disulfates 2 and 3 were determined on the basis of J-based configuration analysis and supported by calculations. The impact of configuration on membrane permeability in Gram-negative bacteria and mammalian cell lines was assessed as well as cytotoxicity. Although diastereomer 2 showed similar behavior to natural (+)-danicalipin A (1), strikingly, the more flexible C11,C15-epimer 3 had no effect on permeability and proved equally or more toxic towards multiple cell lines.

Iron-catalyzed cyclopropanation with glycine ethyl ester hydrochloride in water.

An iron-catalyzed cyclopropanation reaction of styrenes in aqueous media is disclosed that employs glycine ethyl ester hydrochloride in a tandem diazotization/cyclopropanation reaction. The products are accessed in good yields and good diastereoselectivity using readily available and inexpensive starting materials. Moreover, a wide range of transition metals may be used under these conditions, thus opening new opportunities for efficient carbene-transfer reactions under user-friendly conditions.

Stereoselective syntheses of epothilones A and B via nitrile oxide cycloadditions and related studies.

The expedient and fully stereocontrolled synthesis of epothilones A and B are described. The routes described make extensive study of nitrile oxide cycloadditions as surrogates for aldol addition reactions and have led to the realization of a highly convergent synthesis based on the Kanemasa hydroxyl-directed nitrile oxide cycloaddition. As well, our synthetic efforts have led to the development of new reaction methodologies and served as the proving ground for several modern methods for asymmetric carbon-carbon bond formation.

Asymmetric synthesis of gamma-hydroxy alpha,beta-unsaturated aldehydes via enantioselective direct addition of propargyl acetate to aldehydes.

We report the first example of enantioselective and diastereoselective aldehyde additions of propargyl acetate to aldehydes using the methodology recently reported from our laboratories. Subsequent O-silyl protection, Pd-catalyzed isomerization, AcOH addition, and hydrolysis result in optically active gamma-hydroxy alpha,beta-unsaturated aldehydes as powerful building blocks. Reaction: see text.

A mild and chemoselective method for the reduction of conjugated isoxazolines to beta-hydroxy ketones.

A new procedure for the selective reduction of conjugated Delta(2)-isoxazolines to the corresponding unsaturated beta-hydroxy ketones is described. The use of SmI(2) as the reducing agent and B(OH)(3) to hydrolyze the resulting imine results in a mild, convenient, and chemoselective protocol for this otherwise difficult transformation and complements existing methodology for the preparation of beta-hydroxy ketones via nitrile oxides.

Direct addition of TMS-acetylene to aldimines catalyzed by a simple, commercially available Ir(I) complex.

A new, convenient procedure for the addition reaction of trimethylsilylacetylene to imines is described. Simply treating a solution of aldimine and trimethylsilyl acetylene with catalytic [IrCl(COD)](2) furnishes the adduct in preparatively useful yields. Interestingly, the reaction may be conducted in the absence of solvent. [reaction: see text]

The discovery of novel reactivity in the development of C-C bond-forming reactions: in situ generation of zinc acetylides with Zn(II)/R(3)N.

There have been great strides in expanding the scope, application, and versatility of known reaction types (i.e., Mukaiyama aldol). It is interesting to speculate that limitations in the number of such known basic reaction types constitute the greatest barrier in the development of practical processes. The catalytic generation of transition-metal metalloenolates and alkynilides under conditions compatible with electrophilic reaction partners provides fresh avenues for the development of new efficient asymmetric processes leading to C-C bond formation.

N,O-Bis(trifluoroacetyl)hydroxylamine as a useful electrophilic nitrogen source: catalytic synthesis of N-(trifluoroacetyl)sulfilimines.

[formula: see text] In the presence of catalytic quantites of Cu(OTf)2 the novel hydroxamic acid anhydride salt functions competently in the trifluoroacetamidation of sulfides to afford N-(trifluoroacetyl)sulfilimines. The salient features of this salt include its ease of synthesis from the inexpensive, commercially available starting materials trifluoroacetic anhydride and hydroxylamine hydrochloride.