Helvetica Chimica Acta

doi: 10.1002/hlca.19750580401pmid: N/A

Baláspiri, L.; Penke, B.; Papp, Gy.; Dombi, Gy.; Kov´cs, K.

doi: 10.1002/hlca.19750580402pmid: 1158743

Optically pure α‐L‐homoproline can be prepared with good yield from N‐bnezyloxycarbonyl‐L‐proline through its diazoketone‐derivative. Preparation of derivatives of α‐L‐homoproline used in peptide chemistry, and of 7‐α‐L‐homoproline‐bradykinin, as well as biological investigation of the latter are described.

Heller, Werner; Tamm, Christoph

doi: 10.1002/hlca.19750580403pmid: N/A

Purification of crude piscidic acid from ‘Cortex Piscidiae Erythrinae’, the root bark of Piscidia Erythrina L. (Papilionaceae), led to the isolation of fukiic acid (5) and 3′‐O‐methyl‐fukiic acid (8). Since partition chromatography with alcoholic solvents produced the corresponding half‐esters as artefacts, the acids were transformed to their methyl esters before separation. Spectroscopic methods and comparison with authentic samples from Petasites japonicus F. SCHMIDT (Compositae) confirmed the structures 5 and 8.

Hoesch, Lienhard; Dreiding, André S.

doi: 10.1002/hlca.19750580404pmid: N/A

Lead tetraacetate oxidation of N‐aminophthalimide (11) in inert solvents gives as major products phthalimide (15) or trans‐1,4‐bisphthaloyl‐2‐tetrazene (12), the former (15) on slow, the latter (12) on fast addition of the oxidizing agent. As by‐products are found: (a) in the presence of acetic acid: N‐acetylamino‐phthalimide (14), and (b) in its absence (especially at higher temperatures): benzocyclobutenedione (13) along with N‐phthalimido‐phthalimide (16) as well as traces of phthalic anhydride (17).

Agwada, Vincent C.; Morita, Yutaka; Renner, Ulrich; Hesse, Manfred; Schmid, Hans

doi: 10.1002/hlca.19750580405pmid: N/A

From the root bark of the Apocynaceae Gabunia eglandulosa STAPE seven indole alkaloids were isolated. Besides the known indole alkaloids (−)‐isovoacangine (1), (−)‐coronaridine (2), voacamine (3), vobasine (4), and perivine (5), two new bases (−)‐19‐hydroxy‐isovoacangine (6) and 19‐hydroxy‐coronaridine (15) were isolated. Compound 6 was obtained by oxidation of isovoacangine with iodine. Similar oxidation reactions with voacangine (12) were studied.

Näf, Ferdinand; Decorzant, René; Thommen, Walter; Willhalm, Bruno; Ohloff, Günther

doi: 10.1002/hlca.19750580406pmid: N/A

The four geometrical isomers of 1,3,5‐undecatriene, 1a–d have been prepared (stereospecifically and non‐stereospecifically), using either (1) the Wittig reaction, (2) thermal sigmatropic hydrogen shifts, (3) partial reduction of triple bonds by zinc, or (4) organocopper reagents. The thermal behaviour of the four 1,3,5‐undecatrienes has been investigated and the products formed have been characterized. The spectra of 1a–d, and of related compounds, have been discussed in order to corroborate their configurational assignment.

Peter, Martin G.; Dahm, Karl H.

doi: 10.1002/hlca.19750580407pmid: 1158736

In the adult made cecropia moth, 1‐[14C]‐propionate is incorporated specifically into juvenile hormone I (1). By chemical degradation it was found that only C(7) and C(11) are labelled, each carbon atom bearing 50% of the radioactivity originally present in JH‐I. It is concluded that propionate serves as a precursor of homomevalonate, which in turn is a precursor for JH‐I. Application of 2‐[14C]‐propionate and 3‐[14C]‐propionate leads to extensive randomization of the label. Apparently propionate is metabolized such that C(2) and C(3) can be reused as smaller fragments–probably acetate–while C(1) is either highly diluted or removed from the propionate in a metabolically inactive form.

Alder, Alex Peter; Wolf, Hans Richard

doi: 10.1002/hlca.19750580408pmid: N/A

UV.‐irradiation (λ ≥ 327 nm) of the α,β‐unsaturated γ,δ‐epoxy ketone 2 in pentane gives the isomers oxidoketone 3 and diketone 4, in high yield. On treatment with BF3O(C2H5)2, 2 undergoes rearrangement to the diketone 4 and the isomeric lactone 8 and yields also the dimer 9.

Fierz, G.; McGarrity, J. F.; Dahn, Hans

doi: 10.1002/hlca.19750580409pmid: N/A

In the acid hydrolysis of two secondary diazoketones showing rate‐determining protonation, 3‐diazo‐butan‐2‐one (1) and 1‐phenyl‐1‐diazo‐acetone (4), the nature of the (rapid) decomposition step of the intermediate diazonium ion was studied by product analysis. In the presence of strong nucleophiles, the reaction with Cl−, Br−, I− and SCN− follows the Swain‐Scott relationship. SCN− formed thiocyanates; isothiocyanates could not be detected. Both results indicate nucleophilic participation in the substitution step. For the accompanying elimination reaction (the amount of which is independent of added base) the isotope effect kH/kD = 2,4 in the hydrolysis of 1–d3 is in favour of an E2 type mechanism. – Addition of HSCN to methyl‐vinylketone at 0° yields nearly exclusively 4‐thiocyanato‐butan‐2‐one, which at 25° in the presence of HSCN is slowly rearranged to 4‐isothiocyanato‐butan‐2‐one.

Bekaert, Alain; Devys, Michel; Barbier, Michel

doi: 10.1002/hlca.19750580410pmid: N/A

The partial synthesis of pollinastanol (14) from cycloartanol (3) is reported. The transformation proceeds through the methylenic intermediate 12; the ring enlargement with cyanogen azide affords pollinastanone (13) further reduced to 14, The 4‐keto isomer of pollinastanone (17) as well as a series of 5‐β isomeric compounds are also described.