1-benzyl-2- pyrrolidine

It was stated that tertiary amines 304 derived from pyrrolidines [R = alkyl, benzyl, SiMcs, Si(t-Bu)2Me] add very efficiently (yields up to 94%) to (5R)-5-menthyloxy-2(5//)-furanone 170 under photosensitized conditions to give the isomeric adducts 305 and 306 (Scheme 82) (99TL3169). 

Kaiser and Muchowski (41) reduced A -(r-butoxycarbonyl) pyrroles to the corresponding pyrrolidines over 5% Pt-on-C at room temperature and atmospheric pressure. Under these conditions 0-benzyl groups are retained and 2,5-disubstituted pyrroles are reduced mainly or exclusively to thecis-2,5-disubstituted pyrrolidines. In some cases Pt-on-C proved superior to either Rh-on-C or PtO,. 

The best result is obtained with the (.S )-2-(2,6-dimethyl benzyl (pyrrolidine complex (see Appendix) at — 109 °C. On quenching with acid, this yields 79% of a 78 22 kinelically controlled... 

Die Reduktion enolisierbarer /J-Oxo-carbonsaure-ester mitNatriumboranat er-gibt bessere Resultate als mit Lithiumalanat, da kein Olefin gebildet wird (s. S. 215). Aus 4-Oxo-l-benzyl-3-athoxycarbonyl-pyrrolidin erhalt man z. B. das Diol mit Natriumbo-ranat in 72%iger, mit Lithiumalanat in 51%iger Ausbeute. Die selektive Reduktion zum Hydroxy-carbonsaure-ester liefert schlechtere Ergebnisse2 ... 

Zur Reduktion von 4-Oxo-l-benzyl-3-athoxycarbonyl-pyrrolidin s.S. 217. Oxo-lactone werden am besten mit Zinkboranat selektivzu Hydroxy-lactonen re-duziert4,5 mit Natriumboranat wird zusatzlich die Lacton-Gruppe reduktiv gespalten z.B.4 ... 

The reaction can be done intramolecularly. N-Benzyl pent-4-ynamide reacted with tetrabutylammonium fluoride to an alkylidene lactam. Similar addition of a tosylamide-alkene, with a palladium catalyst, led to a vinyl Al-tosyl pyrrolidine. Similar cyclization reactions occur with tosylamide-alkynes. ... 

The M-aUylated compounds may serve as precursors to the M-unsubstituted pyrrolidines by a mild Pd(0) catalyzed deallylation procedure [451. The deallylation may be more straightforward than hydrogenolysis of the M-benzylated product in which complications due to the presence of the oxime and the other Bn moiety (1,2 bond in the pyrrolidine ring) may arise during reduction. Attempts to prepare piperidine and azepine systems following the above procedure were unsuccessful. 

Pyrrolidines have been prepared by 1,3-dipolar cycloaddition of N-(benzyli-dene)trimethylsilylamine/TMSOf 20 and methyl acrylate, N-methylmaleimide, or dimethyl maleate [35]. More recently, methyl trans-3-cyanociruiamate 1479 was reacted with N-benzyl-N-(trimethylsilylmethyl)aminomethyl methyl ether 1480 and trifluoroacetic acid in CH2CI2 at 0°C and 24°C to afford, via 1481, the pyrrolidine derivative 1482 in high yield and MeOSiMe3 13a [35a] (Scheme 9.20). Several... 

Rhodium complexes of (R,i )-1-benzyl-3,4-dithioether-pyrrolidines were also prepared by these authors, who further investigated them as ligands of rhodium complexes in the hydroformylation of styrene but, in all experiments, the enantioselectivity was lower than 3% ee, whereas the chemoselectivity was of 97% (Scheme 10.5). ... 

A propoxyphene-like analgesic which obeys the empirical morphine rule is pyrroliphene (101). A Mannich reaction involving pyrrolidine, formaldehyde and propiophenone gave amino ketone 99, which was converted to tertiary carbinol 100 by reaction with benzyl magnesium chloride reaction with acetyl... 

Bayon and co-workers observed that constrained 1,2-diphosphines such as (3R,4R)-1-benzyl-3,4-/u.v(diphenylphosphino)pyrrolidine (deguphos) form dimeric complexes in addition to the expected monomeric complexes.255... 

The highly enantioselective reductive animation of a-keto acids as a route to amino acids is possible with ligand 118 (3 R,4R)- l-W-benzyl)-3,4-bis(diphenylphosphanyl)pyrrolidine, DEGUPHOS] and [Rh(cod)2]BF4.649 (R,R)-NORPHOS (2-exo-3-endo-bis(diphenylphosphino)bicyclo[2.2.1 ]heptene) and (2. S, 3. S ) - C HIR AP H O S (bis(diphenylphosphino)butane) are also good ligands for this transformation. Arylpyruvic acids give the best results (>95% ee). 

Dipolar cycloaddition reactions between three A-benzyl-C-glycosyl nitrones and methyl acrylate afforded key intermediates for the synthesis of glyco-syl pyrrolidines. It was found that furanosyl nitrones (574) and (575) reacted with methyl acrylate to give mixtures of all possible 3,5-disubstituted isoxazolidines (577) and (578). On the other hand, the reaction with pyranosyl nitrone (576) was much more selective and cycloaddition at ambient temperatures afforded only one of the possible Re-endo adducts (579a). The obtained isoxazolidines were transformed into the corresponding (V-benzyl-3-hydroxy-2-pyrrolidinones (580—582) on treatment with Zn in acetic acid (Scheme 2.264) (773). 

Racemic fra .s-A--benzyl-2.5-bis-(ethoxycarbonyl)pyrrolidine has been resolved via its dicarboxylic acid, followed by subsequent transformation to offer (2R,5R)-21 or (25,5S -21. The absolute configuration of the alkylated carboxylic acids indicates that the approach of alkyl halides is directed to one of the diastereotopic faces of the enolate thus formed. In the following case, the approached face is the 57-face of the (Z)-enolate. By employing the chiral auxiliary (2R,5R)-21 or its enantiomer (25.55)-21. the (/ )- or (S)-form of carboxylic acids can be obtained with considerably high enantioselectivity (Table 2-4). 

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