1993-91-5

Upstream product

• 108-05-4 vinyl acetate 
• 1755-12-0 2-fluorocyclopentanone 
• 285-67-6 Cyclopentene oxide 
• 285-67-6 (1S,5R)-6-Oxa-bicyclo[3.1.0]hexane 

Downstream Products

• 932706-28-0 ((1R,2S)-2-fluorocyclopentyl)isoindolyl-1,3-dione 

Relevant academic research and scientific papers

Synthesis of optically active vicinal fluorocyclopentanols and fluorocyclopentanamines by enzymatic deracemization

All possible stereoisomers of cis- and trans-2-fluorocyclopentan-1-ols were obtained by kinetically controlled deracemization in the presence of lipases in organic media. High enantioselectivities and good yields of stereomers were obtained for all substrates. Optically pure 1,2-fluorocyclopentan-1-ols were converted to 2-fluoro-cyclopentan-1-amines using the Mitsunobu reaction. The absolute configurations were determined using the Kazlauskas rule and chemical correlation. The interaction of substrates with enzymes has considered using Koshland induced fit theory.

Mechanistic investigations of cooperative catalysis in the enantioselective fluorination of epoxides

This report describes mechanistic studies of the (salen)Co- and amine-cocatalyzed enantioselective ring opening of epoxides by fluoride. The kinetics of the reaction, as determined by in situ 19F NMR analysis, are characterized by apparent first-order dependence on (salen)Co. Substituent effects, nonlinear effects, and reactivity with a linked (salen)Co catalyst provide evidence for a rate-limiting, bimetallic ring-opening step. To account for these divergent data, we propose a mechanism wherein the active nucleophilic fluorine species is a cobalt fluoride that forms a resting-state dimer. Axial ligation of the amine cocatalyst to (salen)Co facilitates dimer dissociation and is the origin of the observed cooperativity. On the basis of these studies, we show that significant improvements in the rates, turnover numbers, and substrate scope of the fluoride ring-opening reactions can be realized through the use of a linked salen framework. Application of this catalyst system to a rapid (5 min) fluorination to generate the unlabeled analog of a known PET tracer, F-MISO, is reported.

Asymmetric oxidative α-fluorination of 2-alkylphenylacetaldehydes with AgHF2 and ruthenium/PNNP catalysts

During attempts directed at epoxide ring opening with different HF sources, we discovered that the Lewis acidic [RuCl(PNNP)]+ (1) or [Ru(OEt2)2(PNNP)]2+ (2) catalysts promote the [1,2]-phenyl shift (Meinwald rea

(Salen)chromium Complex Mediated Asymmetric Ring Opening of meso- And Racemic Epoxides with Different Fluoride Sources

The asymmetric ring opening of five meso-and three racemic epoxides with different fluorinating reagents in the presence of stoichiometric or slightly sub-stoichiometric amounts of Jacobsen's enantiopure (salen)chromium chloride complex A gave the corresponding optically active vicinal fluorohydrins. Silver fluoride was used as one of the fluoride sources either in the presence of Bu4N+H2F3- in diethyl ether or in acetonitrile. The latter reactions starting from cyclohexene oxide (1) showed maximum 72% ee in the formed fluorohydrin 2 isolated in 90% yield. From other meso-epoxides such as cyclopentene oxide and cycloheptene oxide the corresponding fluorohydrins were isolated in 80% and 82% yield with 65% and 62% ee, respectively. In case of ring opening under similar conditions of the racemic styrene oxide or phenyl glycidyl ether 83% and 75% of the fluorohydrins with fluorine in the primary position were isolated with 74% ee and 65% ee, respectively. Tetrahydronaphthalene oxide yielded a 2:1 mixture of trans- (23% ee) and cis-2-fluoro-3,4-benzocyclohexenol (2% ee) suggesting competing SN2 and SN1 type ring openings. Other epoxides such as cyclooctene oxide, cis-stilbene oxide and α-methylstyrene oxide did not react or gave the fluorohydrins with very small enantiomeric excess.