5.5- Dimethyl-4-carboxyl-2-pyrrolidone

R = COOCH2CMe3, Dirhodium(II) Tetrakis[neopentyl-2-oxopyrrolidme-5(5)-carboxylate] R = COO(CH2)i7CH3, Dirhodium(II) Tetrakis[octadecyl-2-oxopyrrolidme-5(5)-carboxylate] R = CONMe2, Dirhodium(II) Tetrakis[A, A/ -dimethyl-2-pyrrolidone-5(5)-carboxamide]... 

R,5S)-(-)-6,6-Dimethyl-3-oxabicyclo[3.1,0]hexan-2-one. Highly tnantioselective Intramolecular Cyclopropanation Catalyzed by Dirhodium(ll) Tetrakis[methyl 2-pyrrolidone-5(R)-carboxylate],... 

This is the first detailed procedure for the synthesis of a chiral dirhodium(ll) carboxamide catalyst and its application to intramolecular cyclopropanation. The preparation of the ligand, methyl 2-pyrrolidone-5(R)-carboxylate, is adapted from the procedure of Ackermann, Matthes, and Tamm.2 The method for ligand displacement from dirhodium(ll) tetraacetate is an extension of that reported for the synthesis of dirhodium(ll) tetraacetamide.6 The title compound, (1 R,5S)-(-)-6,6-dimethyl-3-oxabicyclo[3.1.0]hexan-2-one, is a synthetic precursor to (1 R,3S)-(+)-cis-chrysanthemic acid.5... 

This collection begins with a series of three procedures illustrating important new methods for preparation of enantiomerically pure substances via asymmetric catalysis. The preparation of 3-[(1S)-1,2-DIHYDROXYETHYL]-1,5-DIHYDRO-3H-2.4-BENZODIOXEPINE describes, in detail, the use of dihydroquinidine 9-0-(9 -phenanthryl) ether as a chiral ligand in the asymmetric dihydroxylation reaction which is broadly applicable for the preparation of chiral dlols from monosubstituted olefins. The product, an acetal of (S)-glyceralcfehyde, is itself a potentially valuable synthetic intermediate. The assembly of a chiral rhodium catalyst from methyl 2-pyrrolidone 5(R)-carboxylate and its use in the intramolecular asymmetric cyclopropanation of an allyl diazoacetate is illustrated in the preparation of (1R.5S)-()-6,6-DIMETHYL-3-OXABICYCLO[3.1. OJHEXAN-2-ONE. Another important general method for asymmetric synthesis involves the desymmetrization of bifunctional meso compounds as is described for the enantioselective enzymatic hydrolysis of cis-3,5-diacetoxycyclopentene to (1R,4S)-(+)-4-HYDROXY-2-CYCLOPENTENYL ACETATE. This intermediate is especially valuable as a precursor of both antipodes (4R) (+)- and (4S)-(-)-tert-BUTYLDIMETHYLSILOXY-2-CYCLOPENTEN-1-ONE, important intermediates in the synthesis of enantiomerically pure prostanoid derivatives and other classes of natural substances, whose preparation is detailed in accompanying procedures. 

Abbreviations acac, acetylacetonate acam, acetamide, BINAP, binaphtholphosphate BN OX, 4-benzyl-2-oxazolidinone cap, caprolactamate DM AD, dimethyl acetylenedicarboxy-late hfacac, hexafluoroacetylacetonate MACIM, methyl l-acetylimidazolidin-2-one-4-carboxylate MEPY, methyl 2-pyrrolidone-5-carboxylate MEOX, methyl 2-oxazolidinone-4-carboxylate NPMI, A-phenylmaleimide pfb, perfluorobutyrate oct, octanoate TEBA, benzyltriethylammonium chloride tfa, trifluoroacetamidate. 

In addition to polymer latexes, inorganic suspensions may also be formed in CO2. (10) Block copolymers have been shown by turbidimetry to stabilize 1 pm hydrophilic silica dispersions in CO2, with stability decreasing in the order PS-Z)-PFOA > poly(methyl methacrylate-co-hydroxyethyl methacrylate)-g-PFPE > poly(dimethyl-siloxane)-g-pyrrolidone carboxylic acid (PDMS-g-PCA) (MW 8500 g/mol, 2 PCA groups). The decrease in stability with decreasing CO2 density was sharper for higher molecular weight C02-philic segments, as expected based on the nature of polymer chain collapse. 

R,5S)-(-)-6,6-DIMETHYL-3-OXABICYCLO[3.1.0]HEXAN-2-ONE. HIGHLY ENANTIOSELECTIVE INTRAMOLECULAR CYCLOPROPANATION CATALYZED BY DIRHODIUM(II) TETRAKIS[METHYL 2-PYRROLIDONE-5(R)-CARBOXYLATE]... 

When we applied the Stahl conditions to the copper-catalyzed coupling of (dimethyl 5-oxopyrrolidine-2-carboxylate (III-54) and Af-Boc ethynylindole derivate III-8IB0C, only the Glaser-Hay product III-83 was isolated together with starting material (Scheme 4.52). This result did not surprise us, since Stahl had reported the same problem during the coupling of 2-pyrrolidone and phenylacetylene (Fig. 4.10). 

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