Organocatalytic Highly Enantioselective Tandem Michael-Knoevenagel Reaction for the Synthesis of Substituted Thiochromanes.

Enantioenriched tetrasubstituted thiochromanes have been synthesized using a tandem Michael addition-Knoevenagel reaction between 2-mercaptobenzaldehydes and benzylidenemalonates with a 9-epi-aminoquinine thiourea derivative as the catalyst. Steric and electron effects were found to affect profoundly the enantioselectivity and diastereoselectivity of the reaction.

Synthesis of 2,3,4-Trisubstituted Thiochromanes using an Organocatalytic Enantioselective Tandem Michael-Henry Reaction.

Enantioenriched 2,3,4-trisubstituted thiochromanes have been synthesized by using a cupreine-catalyzed tandem Michael addition-Henry reaction between 2-mercaptobenzaldehydes and ß-nitrostyrenes. Good diastereoselectivities and enantioselectivities were obtained for the title compounds, which may be further improved through a single recrystallization (up to 98% de and> 99% ee).

Silver(I) triflate-catalyzed direct synthesis of N-PMP protected alpha-aminopropargylphosphonates from terminal alkynes.

[reaction: see text] N-PMP protected alpha-aminopropargylphosphonates have been synthesized by using a silver(I) triflate-catalyzed one-pot three-component reaction of terminal alkynes, p-anisidine, and diethyl formylphosphonate hydrate. Good to excellent yields of the desired products may be obtained with a very simple procedure.

Enantioselective synthesis of alpha-aminopropargylphosphonates.

alpha-Aminopropargylphosphonates have been synthesized for the first time in good yields and enantiomeric excesses (up to 81% ee) by using a copper(I)-pybox complex as the catalyst.

Organocatalytic highly enantioselective synthesis of secondary alpha-hydroxyphosphonates.

[reaction: see text] The first organocatalytic cross aldol reaction of ketones and diethyl formylphosphonate hydrate has been realized by using readily available l-prolinamide as the catalyst. Secondary alpha-hydroxyphosphonates have been synthesized in high enantioselective (up to >99% ee) and good diastereoselectivity.

C2-symmetric bisprolinamide as a highly efficient catalyst for direct aldol reaction.

[reaction: see text] The catalytic activity of the prolinamide-type catalysts may be improved by introducing additional prolinamide moiety into the catalyst, while the enantioselectivity can still be maintained or further improved. A C2-symmetric bisprolinamide with two prolinamide moieties has been found to be an excellent catalyst for direct aldol reaction with more than doubled reactivity and better asymmetric induction than its monoprolinamide counterpart.

Fungichromin: a substance from Streptomyces padanus with inhibitory effects on Rhizoctonia solani.

Streptomyces padanus strain PMS-702 is an antagonist of Rhizoctonia solani AG-4, the causal agent of damping-off of cabbage. Treatment of cabbage seeds with the culture filtrate of S. padanus strain PMS-702 was effective in reducing the incidence of damping-off of cabbage. The major active ingredient from the culture filtrate of S. padanus strain PMS-702 was purified by silica gel column chromatography and identified as the polyene macrolide, fungichromin, by NMR and mass spectral data. Bioassay studies showed that fungichromin had a strong antifungal activity against R. solani AG-4, and its minimum inhibitory concentration (over 90% inhibition) was found to be 72 microg/mL. This is the first report of fungichromin from S. padanus as an active ingredient for the control of Rhizoctonia damping-off of cabbage.