Epi-lupinine

Recently, lupinine 4 and epi-lupinine 139 were also synthesized by Takayama s group (85H2913) based on an intramolecular imino Diels-Alder reaction (Scheme 20). Thermolysis of acetate 141 in toluene containing sodium hydrogen carbonate in a sealed tube at 200 C for 2 hr gave lactam 143 in 80% yield via desulfonylation and subsequent intramolecular cycloaddition of 142. 

C,oH NO, Mr 169.27, mp. 68.5-69.2°C, bp. 269-270 °C, [alo -21° (C2H5OH) racemate, mp. 63 - 64°C (59 °C). L. and the 5-epimer epi-lupinine mp. 77-78°C, [alo +32° (CjHjOH)) are quinolizidine alkaloids of which only few members contain the bicyclic lupinine type structure. They occur in several Fabaceae genera . L. is also a component of the Che-nopodiaceae Anabasis aphylla. In addition, esters of epi-lupinine with acetic, coumaric, and ferulic acid are known as natural products. Several syntheses, some enantiosclective, of these simple quinolizidine alkaloids have been reported. ... 

It is noteworthy that, in the corollary intramolecular imino Diels-Alder reaction reported by Weinreb et al where A-acyl imines are employed as heterodienophiles [21], exclusive preference for boat-like transition states is observed, wherein the carbonyl group is restrained in the s-cis conformation within the A-acyl imine and approach is endo to the diene (Scheme 2.8). For example, in the intramolecular acyl imine Diels-Alder reaction en route to the synthesis of the quinolizidine alkaloids epi-lupinine (56) and lupinine (57) ... 

Schdpf and Thoma found that lupininic acid yielded a methyl ester (b.p. 120-2°/10 mm.) which had [aj — 19-4° to 5-8° in different batches. The f-ester furnished a gummy picrate, [a]J, ° — 41-8°, and on hydrolysis by hydrochloric acid gave a crystalline lupininic acid hydrochloride, m.p. 275°, — 13T°, identical with that described by Willstatter and Fourneau, whilst the d-ester, or ester of f-rotation below — 19-4°, furnished a crystalline picrate, m.p. 185°, [a]j, -f- 61-8°, from which pure d-epi-ester,-b.p. 126°/11 mm., [aJi, 54-8°, was prepared, this in turn yielding amorphous d-lupininie acid hydrochloride. The f-ester is convertible into ... 

Auch bei 5-, 6- und 7-Ringsystemen lassen sieh photochemische Isomerisierungen bcobachten. Aus Lupinin (6-Hydroxymethyl-l-aza-bicyelo 4.4.0 decan) erhalt man Epi-lupinin1 ... 

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