135905-08-7

Upstream product

• 76513-69-4 (2-trimethylethylsilylethoxy)methyl chloride 
• 135904-96-0 (2SR,3SR,βSR)-1-(Benzyloxycarbonyl)-3-hydroxy-β-(prop-2-en-1-yl)pyrrolidine-2-ethanol 
• 135904-95-9 (1SR,4SR,5SR)-6-(Benzyloxycarbonyl)-4-(prop-2-en-1-yl)-2-oxa-6-azabicyclo<3.3.0>octan-3-one 
• 95456-65-8 (3aR,6aR)-2-Oxo-hexahydro-furo[3,2-b]pyrrole-4-carboxylic acid benzyl ester 
• 501-53-1 benzyl chloroformate 

Downstream Products

• 135905-09-8 (2R,3R)-2-[(R)-3-Methanesulfonyloxy-1-(2-trimethylsilanyl-ethoxymethoxymethyl)-propyl]-3-(2-trimethylsilanyl-ethoxymethoxy)-pyrrolidine-1-carboxylic acid benzyl ester 
• 135905-10-1 (2SR,3SR,γSR)-1-(Benzyloxycarbonyl)-3-<2-(trimethylsilyl)ethoxymethoxy>-γ-<2-(trimethylsilyl)ethoxymethoxymethyl>pyrrolidine-2-propanol 

Relevant academic research and scientific papers

Homoproline homologation by enolate Claisen rearrangement or direct allylation: Syntheses of (-)-trachelanthamidine, (-)-isoretronecanol and (±)-turneforcidine

The pyrrolizidine precursors 13 and 14 are obtained both by enolate Clalsen rearrangement of the homoproline allyl ester 12 and by direct allylation of N-protected homoproline ethyl ester 15. In both cases, the reactions show poor levels of stereoselectivity. Reduction gives the corresponding alcohols 20a and 21 a which are separated and subsequently elaborated to (-)-trachelanthamidine 24 and (-)-isoretronecanol 25 respectively via reductive alkene cleavage, mesylation and spontaneous cyclisation following N-deprotection. The chiral integrity of the original proline-derived asymmetric centre is preserved throughout. A similar enolate allylation gives, with high stereoselectivity, the homologue 34 of the Geissman-Waiss lactone 32, which is similarly transformed into (±)-turneforcidine 31.

Synthesis of Necine Bases from Homoproline Derivatives

The α-allyl homoproline ester 8, obtained by Claisen rearrangement of the allyl ester 7 or direct C-allylation of the homoproline methyl ester 9 has been converted into (-)-trachelanthamidine 4a and (-)-isoretronecanol 4b while allylation of the enolate derived from the lactone 13a followed by related transformations leads stereospecifically to turneforcidine 12.