Twenty years of gibberellin research

This review covers research into the chemistry and biology of the gibberellin family of plant bioregulators carried out in the author's laboratory over the past 20 years and has 231 references.     

Alkaloids from marine organisms. Part 8: Isolation of bisdemethylaaptamine and bisdemethylaaptamine-9-O-sulfate from an Indonesian Aaptos sp. marine sponge

Bisdemethylaaptamine (6), a proposed biosynthetic precursor of the aaptamines has been isolated from an Aaptos sp. marine sponge harvested off the Indonesian coast, and its identity confirmed by comparison of its spectral data with that of synthetic material. Bisdemethylaaptamine-9-O-sulfate (7) was also isolated from the same source. This is the first report of a sulfated aaptamine.     

An Oxidant- and Organic Solvent-Resistant Alkaline Metalloprotease from Streptomyces olivochromogenes

Organic solvent- and detergent-resistant proteases are important from an industrial viewpoint. However, they have been less frequently reported and only few of them are from actinomycetes. A metalloprotease from Streptomyces olivochromogenes (SOMP) was purified by ion exchange with Poros HQ and gel filtration with Sepharose CL-6B. Apparent molecular mass of the enzyme was estimated to be 51 kDa by sodium dodecyl sulfate–polyacrylamide gel electrophoresis and gelatin zymography. The activity was optimum at pH 7.5 and 50 °C and stable between pH 7.0 and 10.0. SOMP was stable below 45 °C and Ca²⁺ increased its thermostability. Ca²⁺ enhanced while Co²⁺, Cu²⁺, Zn²⁺, Mn²⁺, and Fe²⁺ inhibited the activity. Ethylenediaminetetraacetic acid and ethylene glycol-bis (β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid, but not phenylmethylsulfonyl fluoride, aprotinin, and pefabloc SC, significantly suppressed the activity, suggesting that it might be a metalloprotease. Importantly, it is highly resistant against various detergents, organic solvents, and oxidizing agents, and the activity is enhanced by H₂O₂. The enzyme could be a novel protease based on its origin and peculiar biochemical properties. It may be useful in biotechnological applications especially for organic solvent-based enzymatic synthesis.     

Reductive alkylation of 2-methoxybenzoic acid derivatives

Metal-ammonia reduction followed by in situ alkylation of 2-methoxybenzoic acids often results in substantial loss of the methoxy substituent; reduction of the carboxylate salts or esters, however, suppresses this side reaction and good to excellent yields of desired products are then obtained.     

Model studies toward the synthesis of the bioactive diterpenoid, harringtonolide

In model studies towards the synthesis of harringtonolide, the construction of the tropone moiety via arene cyclopropanation was investigated. The installation of the lactone ring was accomplished by way of a Diels-Alder cycloaddition of various indenones and a-pyones. The incorporation of the key bridge methyl group and subsequent control of its stereochemistry is also outlined.     

Methodology for translocating the carboxy group in gibberellins: the partial synthesis of 7(6→15βH)abeo-GA4

The carboxylic acid group has been excised from phytohormone gibberellin A₄ and relocated on the D-ring, thereby generating a new clas of gibberellin derivatives related structurally to helminthosporic acid.     

A Refined Method for the Removal of the Methoxymethyl (MOM) Protecting Group for Carbinols with Acidic Ion-Exchange Resin

The methoxymethyl protecting group for carbinols is best removed from acid-sensitive substrates by hydrolysis in aqueous methanol using a cationic exchange resin (Dowex-50W).     

A formal total synthesis of the marine diterpenoid diisocyanoadociane

[Structure: see text] A formal total synthesis of diisocyanoadociane, a marine diterpenoid with potent antimalarial properties, has been completed. The synthesis begins with a phenanthrenoid precursor that is transformed into a pyrene-derived intermediate by means of an intramolecular Michael reaction. Nitrogen functionality is introduced via a double Curtius reaction.     

Bridgehead arylation: a direct route to advanced intermediates for the synthesis of C-20 diterpene alkaloids

[reaction: see text] Rapid access to the ABCE ring system of the C(20) diterpene alkaloids was achieved by silver(I)-promoted intramolecular Friedel-Crafts arylation of a functional group-specific 5-bromo-3-azabicyclo[3.3.1]nonane derivative.     

Synthesis of t-butyldimethylsilyl enol ethers from sterically hindered ketones

Ketones react rapidly with $\text{t}$-butyldimethylsilyl triflate and amine bases to form $\text{t}$-butyldimethylsilyl enol ethers in high yields.