Synthesis of indolizidines from optically pure α-amino acids via stereocontrolled rhodium-catalyzed hydroformylation of N-allylpyrroles.

Synthesis of indolizidines from optically pure α-amino acids via stereocontrolled rhodium-catalyzed hydroformylation of N-allylpyrroles.

Chirality (2011-08-23)

Raffaello Lazzaroni, Roberta Settambolo

ABSTRACT

Indolizidine alkaloids have attracted considerable attention because of their vast array of structural diversity and varied biological activity. This article relates the results that we obtained in the field of the total synthesis of indolizidines from α-amino acids, based on the rhodium-catalyzed hydroformylation of N-allylpyrroles intermediates. The formed pyrrolylbutanals undergo an intramolecular cyclodehydration to 5,6-dihydroindolizines, which are fully hydrogenated to indolizidines. All reaction sequences are stereocontrolled: indeed, the chiral center in the starting amino acid is transferred into 5,6-dihydroindolizine moiety with complete stereochemical integrity and the new stereogenic center at C9 carbon atom in the final indolizidines is generated in only one configuration.

MATERIALS

Product Number

Brand

Product Description

204218

Sigma-Aldrich

Rhodium, powder, 99.95% trace metals basis

GF24911726

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GF22634120

Rhodium, foil, not light tested, 50x50mm, thickness 0.00075mm, permanent polyester support, 99.85%

GF44569907

Rhodium, foil, 25x25mm, thickness 0.125mm, as rolled, 99.9%

GF49946417

Rhodium, microfoil, disks, 10mm, thinness 0.50μm, specific density 620μg/cm², permanent mylar 3.5μm support, 99.99%

GF36379345

Rhodium, foil, light tested, 15x15mm, thickness 0.05mm, as rolled, 99.9%

GF49036204

Rhodium, foil, not light tested, 25x25mm, thickness 0.00075mm, permanent polyester support, 99.85%

GF15499413

Rhodium, foil, not light tested, 25x25mm, thickness 0.006mm, as rolled, 99.9%

GF14938005

Rhodium, microfoil, disks, 25mm, thinness 0.1μm, specific density 124μg/cm², permanent mylar 3.5μm support, 99.9%

GF87742659

Rhodium, foil, not light tested, 25x25mm, thickness 0.001mm, permanent polyester support, 99.85%

GF81993910

Rhodium, foil, not light tested, 50x50mm, thickness 0.006mm, as rolled, 99.9%

GF57675561

Rhodium, foil, light tested, 25x25mm, thickness 0.05mm, as rolled, 99.9%

GF82366342

Rhodium, foil, not light tested, 50x50mm, thickness 0.00025mm, permanent polyester support, 99.9%

GF54466937

Rhodium, wire reel, 0.5m, diameter 0.12mm, as drawn, 99.9%

GF64213680

Rhodium, wire reel, 0.05m, diameter 0.12mm, as drawn, 99.9%

GF12568013

Rhodium, foil, light tested, 25x25mm, thickness 0.05mm, as rolled, x-ray quality, 99.9%

GF40539405

Rhodium, foil, 25x25mm, thickness 0.1mm, as rolled, 99.9%

GF45819995

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GF96356559

Rhodium, foil, light tested, 25x25mm, thickness 0.075mm, as rolled, 99.9%

GF71687357

Rhodium, microfoil, disks, 10mm, thinness 0.1μm, specific density 124μg/cm², permanent mylar 3.5μm support, 99.9%

GF04978963

Rhodium, foil, not light tested, 10x10mm, thickness 0.012mm, as rolled, 99.9%

GF72510364

Rhodium, wire reel, 0.5m, diameter 0.25mm, hard, 99.9%

GF33789550

Rhodium, foil, not light tested, 50x50mm, thickness 0.001mm, permanent polyester support, 99.85%

GF26710680

Rhodium, wire reel, 0.1m, diameter 0.12mm, as drawn, 99.9%

GF83497652

Rhodium, wire reel, 0.05m, diameter 1.0mm, as drawn, 99.9%

GF74452316

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GF35442727

Rhodium, foil, not light tested, 25x25mm, thickness 0.0005mm, permanent polyester support, 99.85%

GF80841146

Rhodium, foil, 25x25mm, thickness 0.15mm, as rolled, 99.9%

GF17514312

Rhodium, foil, not light tested, 25x25mm, thickness 0.00025mm, permanent polyester support, 99.9%

GF06539979

Rhodium, wire reel, 0.1m, diameter 0.5mm, as drawn, 99.9%