Alan J. Freyer

Synthesis of the tricyclic portions of batzelladines A, B and D. Revision of the stereochemistry of batzelladines A and D

Abstract The tricyclic portion 4 of batzelladine B ( 2 ) is obtained from 10a , which differs in one side chain from the ptilomycalin A model 10c that we prepared several years ago, by reduction with NaBH 3 CN in buffered MeOH. Hydrogenation of 11b over Rh Al 2 O 3 at 50 PSI H 2 affords the proposed tricyclic portion 12b of batzelladine A ( 1 ). Epimerization of 12b and hydrolysis affords acid 3 , which is similar to, but different from, the acid obtained from hydrolysis of 1 . A five step sequence converts 7b to the anti tricyclic acid 15 , which is identical to the hydrolysis product of 1 . The stereochemistry of the hydrolysis product 15 was confirmed by NOE experiments.

(±)-nuevamine, an isoindoloisoquinoline alkaloid, and (±)-lennoxamine, an isoindolobenzazepine

Abstract Berberis darwinii Hook (Berberidaceae) has yielded the lactams (±)-nuevamine (7) and (±)-lennoxamine (8). Nuevamine is the first known isoindoloisoquinoline alkaloid, while lennoxamine is an isoindolobenzazepine structurally related to (±)-chilenine (3).

Frondosins, five new sesquiterpene hydroquinone derivatives with novel skeletons from the sponge Dysidea frondosa: Inhibitors of interleukin-8 receptors

Abstract Bioassay-guided fractionation of the EtOAc extract of the sponge Dysidea frondosa collected in Pohnpei yielded five sesquiterpenes, frondosins A - E ( 1–5 ). The structures and relative stereochemistry of the frondosins were established by interpretation of spectral data. Frondosins A - E ( 1–5 ), which possess novel carbon skeletons, were found to be inhibitors of interleukin-8 receptors and protein kinase C in the low micromolar range.

Enzyme-mediated coupling of 3,4-dichloroaniline and ferulic acid: a model for pollutant binding to humic materials.

To investigate the incorporation of chloroanilines into humic substances, the reaction of ferulic acid with three different chloroanilines in the presence of a laccase of the fungus Rhizoctonia praticola was investigated. Under the reaction conditions used, chloroanilines alone were not transformed by the laccase, but in the presence of ferulic acid they formed cross-coupling products. The reactivity of anilines decreased with increasing chlorine substitution on the ring. Two dimeric compounds were isolated from the reaction assay of ferulic acid alone. The dimers were found to have phenylcoumaran and lactone structures

The isoindolobenzazepine alkaloids

Abstract Three Chilean barberries, Berberis actinacantha Mart. ex Schult., B . darwinii Hook and [ulbar|B. valdiviana Phil. (Berberidaceae), have yielded several new isoindolobenzazepine and protoberberine alkaloids. Novel isoindolobenzazepines are (±)-13-deoxychilenine ( a ), pictonamine ( 10 ), chileninone ( 12 ), (±)-chileniimi ( 18 ) and (±)-palmanine ( 19 ). Highly oxidized protoberberines of particular interest include (±)-O-methylprechilenine ( 6 ) and (±)-prepseudopalmanine ( 21 ), together with 13-methoxy-8-oxyberberine ( 8 ). Isoindolobenzazepine alkaloids arise biogenetically from the rearrangement of highly oxidized protoberberines.

Magallanesine: an isoindolobenzazocine alkaloid

Abstract Berberis darwinii Hook.(Berberidaceae) has yielded magallanesine ( 1 ), the first known isoindolobetizazocine alkaloid.

Fasicularin, a novel tricyclic alkaloid from the ascidian Nephteis fasicularis with selective activity against a DNA repair-deficient organism

Abstract A novel tricyclic alkaloid, fasicularin (1), was isolated from the Micronesian ascidian Nephteis fasicularis. The structure of 1 was elucidated primarily by interpretation of spectral data. Fasicularin was found to be active in a DNA damaging assay.

The plakortones, novel bicyclic lactones from the sponge Plakortis halichondrioides: Activators of cardiac SR-Ca2+-pumping ATPase

Abstract Bioassay-guided fractionation of the EtOAc extract of sponge Plakortis halichondrioides yielded four novel bicyclic lactones, plakortones A, B, C, D and a novel acid, plakortide E ( 3, 4, 5, 6 and 7 ). The structures, including stereochemistry, of these compounds were established by interpretation of spectral data. Plakortones A-D ( 3–6 ) comprise a novel class of activators of cardiac SR-Ca 2+ -pumping ATPase which were found to be active at micromolar concentrations As part of an SAR study, the α and β diols 9 and 10 of plakortone D were prepared using Sharpless AD procedure.

Generation and intramolecular cationic cyclizations of N-tosylimines derived from enolizable aldehydes

Abstract Boron trifluoride etherate promotes both in situ formation of N-tosyliminium complexes from olefinic enolizable aldehydes and N-sulfinyl-p-toluenesulfonamide, and subsequent intramolecular electrophilic cyclization to afford homoallylic amines.

PULCHERRIMINS A - D, NOVEL DITERPENE DIBENZOATES FROM CAESALPINIA PULCHERRIMA WITH SELECTIVE ACTIVITY AGAINST DNA REPAIR-DEFICIENT YEAST MUTANTS

Abstract Bioassay-guided fractionation of the MeOH/CH2Cl2 extract of the roots of Caesalpinia pulcherrima yielded four novel dibenzoate diterpenes, pulcherrimins A, B, C and D (1–4). The structures of these compounds including their absolute configuration were established by interpretation of spectral data and CD measurements. Pulcherrimins A and B (1 and 2) were found to be active in DNA repair-deficient yeast mutant. Bioassay-guided fractionation of the MeOH/CH2Cl2 extract of the roots of Caesalpinia pulcherrima yielded four novel dibenzoate tetracyclic diterpenes, pulcherrimins A, B, C and D (1–4_. The structures of these compounds including their absolute configuration were established by interpretation of spectral data and CD measurements. Pulcherrimins A and B (1 and 2)_ were found to be active in DNA repair-deficient yeast mutant.