Implementation of Biocatalysis in Continuous Flow for the Synthesis of Small Cyclic Amines

Significant progress has been made in establishing transaminases as robust biocatalysts for the green and scalable synthesis of a diverse range of chiral amines. However, very few examples on the amination of small cyclic ketones have been reported. Cyclic ketones are particularly challenging for transaminase enzymes because they do not display the well-defined small and large substituent areas that are characteristic for the bio- catalytic mechanism. In this work, we exploited the broad substrate scope of the (S)-selective transaminase from Halomonas elongata (HeWT) to develop an efficient biocatalytic system in continuous flow to generate a range of small cyclic amines which feature very often in pharmaceuticals and agrochemicals. [3] Tetrahydrofuran-3-one and other challenging prochiral ketones were rapidly (5–45 min) transformed to their corresponding amines with excellent molar conversion (94–99%) and moderate to excellent ee.

Synthesis of Cyclopentenones with Reverse Pauson-Khand Regiocontrol via Ni-Catalyzed C–C Activation of Cyclopropanone

A formal [3+2] cycloaddition between cyclopropanone and alkynes via Ni-catalyzed C–C bond activation has been developed, where 1-sulfonylcyclopropanols are employed as key precursors of cyclopropanone in the presence of trimethylaluminum. The transformation provides access to 2,3-disubstituted cyclopentenones with complete regiocontrol, favoring reverse Pauson-Khand products where the large substituent is located at the 3-position of the ring. In the process, the trimethylaluminum additive is thought to play multiple roles, including as a Brønsted base triggering the equilibration to cyclopropanone and liberation of methane, as well as a source of Lewis acid to activate the carbonyl group toward Ni-catalyzed C–C activation.

Synthesis of Cyclopentenones with Reverse Pauson-Khand Regiocontrol via Ni-Catalyzed C–C Activation of Cyclopropanone

A formal [3+2] cycloaddition between cyclopropanone and alkynes via Ni-catalyzed C–C bond activation has been developed, where 1-sulfonylcyclopropanols are employed as key precursors of cyclopropanone in the presence of trimethylaluminum. The transformation provides access to 2,3-disubstituted cyclopentenones with complete regiocontrol, favoring reverse Pauson-Khand products where the large substituent is located at the 3-position of the ring. In the process, the trimethylaluminum additive is thought to play multiple roles, including as a Brønsted base triggering the equilibration to cyclopropanone and liberation of methane, as well as a source of Lewis acid to activate the carbonyl group toward Ni-catalyzed C–C activation.

Incorporation of large guest molecules into liposomes via chemical reactions in lipid membranes

Stable lipid-membrane-incorporated fullerene derivatives with large substituent(s) were prepared by Diels–Alder reactions in lipid membranes.

Synthesis and Bleaching Activity of 1-Ethyl-and 1 -Propy 1-5-Substituted Imidazoles

Twenty-eight 1-ethyl-and 1-propyl-5 -substituted imidazoles were synthesized an d their bleaching activity was evaluated by using the lettuce seedling test. 5-Phenyl-1-propylim idazole (1) caused distinct chlorosis, while none of the c ompounds with various alkenyl groups at the 5-position o the imidazole ring show ed this bleaching activity. Introduction of a bromo, chloro, fluoro, methyl or trifluoromethyl groupa t the 4-position on the benzene ring of com­pound 1 increased the activity in comparison with that of compound 1. 5-[4-(3-Chlorobenzyl-oxy)phenyl]-l-ethylimidazole (15) an d l-ethyl-5-[4-(3-methylbenzyloxy)phenyl]imidazole (21), analogs with a large substituent at the 4 -position on the benzene ring, also caused pronounced chlorosis in the lettuce seedlings. Both compounds 1 and 15 a t 30 ppm decreased total c arot­enoid content in the lettuce seedlings to less than 40% of that in the control, and the reduction of total carotenoid content correlated well with treatment dose.

The preparation and characterization of 2-propylphosphinediacetic acid

Phosphineacetic acids of the RP(CH2COOH)2 type, where R is a large substituent with a +I-effect, cannot be prepared by the reaction of chlorophosphine with an organozinc compound because of the lability of the P-CH2COO bonds. The bis(ethyl ester) of 2-propylphosphinediacetic acid as the simplest substance of this kind was prepared by the reaction of chlorophosphine with ethylacetate enolate, which is universal for these substituents. 2-Propylphosphinediacetic acid, obtained from the ester by the usual procedure, was characterized with respect to its use as a hydrophilic phosphine ligand.