A highly enantioselective synthesis of 5- (ι-menthyloxy) -4-substituted-3-chloro-2(5H) -furanones

In this paper, stereocontrolled tandem Michael addition-elimination reaction of the novel chiral source, S-(ι-menthyloxy)-3,4-dichloro-2(5H)-furanone, with various thiols and amines has been investigated. A series of new enantiomerically pure compounds, 5-(ι-menthyloxy)-4-substituted-3-cnloro-2(5H)-furanones, were obtained in good yields with d. e.(?)98% under mild conditions.

Approach to synthesis of novel chiral 3-chloro-2(5H)- furanone and its application in asymmetric reactions

The synthetic method of the novel chiral synthon, 5-/-menthyloxy-3-chloro-2-(5H)-furanone 5a and its application in asymmetric reactions were investigated. 5a is easily obtained in highly optical purity, and acts as a stable acceptor of Michael addition with oxygen nucleophiles in tandem double Michael addition / internal nucieophilic substitution to offer the spiro-cyclopropane derivative containing four stereogenic centers 8, which it is difficult to obtain by routine methods. The synthetic methods for 5a and 8 are reported in detail and the new compounds are identified on the basis of their analytical data and spectroscopic data, such as UV, IR, H NMR,13 C NMR, MS and elementary analysis. The absolute configuration of the interesting spiro-cyclopropanes, spiro [1-chloro-4-(/-menthyloxy)-5-oxo-6-oxa-biscyclo[3.1.0]hexane-2,3i(4’-/-menthyloxy-5’-/-menthyloxy- butyrolactone)] 8 was established by X-ray crystallography. This result can provide important synthetic strategy in synthesis of some complex

Studies on the Chemical Components of Clematis chinensis

Two novel compounds, clemaphenol A and dihydro-4-hydroxy-5-hyroxymethyl-2(3H)-fura-none were isolated together with eight known compounds, isoferulic acid, b-sitosterol, daucosterol, 5-hy-droxymethyl-2-furancarboxaldehyde, 5-hydroxy-4-oxo-pentanoic acid, palmitic acid, linoleic acid and anemonin from the root of Clematis chinensis Osbeck.

Responses of bacterial strains isolated from drinking water environments to N-acyI-L-homoserine lactones and their analogs during biofilm formation

Often as a result ofbiofilm formation, drinking water distribution systems （DWDS） are regularly faced with the problem of microbial contamination. Quorum sensing （QS） systems play a marked role in the regulation of microbial biofilm formation; thus, inhibition of QS systems may provide a promising approach to biofilm formation control in DWDS. In the present study, 22 bacterial strains were isolated from drinking water-related environments. The following properties of the strains were investigated： bacterial biofilm formation capacity, QS signal molecule N-acyl-L-homoserine lactones （AHLs） production ability, and responses to AHLs and AHL analogs, 3-chloro-4-（dichloromethyl）-5-hydroxy-2（5H）- furanone （MX） and 2（5H）-furanone. Four AHLs were added to developed biofilms at dosages ranging from 0.1 nmol.L J to 100nmol.L1. As a result, the biofilm growth of more than 1/4 of the isolates, which included AHL producers and non-producers, were significantly promoted. Further, the biofilm biomasses were closely associated with respective AHLs concentrations. These results provided evidence to support the idea that AHLs play a definitive role in biofilm formation in many of the studied bacteria. Meanwhile, two AHLs analogs demon- strated unexpectedly minimal negative effects on biofilm formation. This suggested that, in order to find an applicable QS inhibition approach for biofilm control in DWDS, the testing and analysis of more analogs is needed.

Synthesis of spiro-cyclopropane derivatives containing multiple chiral centers

Tandem asymmetric double Michael addition/internal nucleophilic substitution of the novel chiral source, 5-(l-menthyloxy)-3-bromo-2(5H)-furanone with nucleophilic alcohol compounds has been investigated. The tandem asymmetric reaction can afford four new stereogenic centers with one reaction and give optically pure spiro-cyclopropane derivatives 5a--5d which are difficult to obtain by routine methods. The synthetic method for 5a--5d was studied in detail and the new compounds were identified on the basis of their analytical data and spectroscopic data, such as [α]^(20),IR,~1H NMR,^(13)C NMR, MS and elementary analysis. The absolute configuration of the sprio [5-l-menthyloxy-3-bromo butyrolactocyclopropane-3″, 3′(4′-methyloxy-5′-menthyloxybutyrolactone)] (5a) was established by X-ray crystallography. The work can provide important synthetic strategy in synthesis of some new optically active spiro-cyclopropane analogues and some biologically active molecules with complex structure.