Mild Epoxidation of Allylic Alcohols Catalyzed by Titanium(III) Complexes: Selectivity and Mechanism

A novel methodology for the epoxidation of a broad range of primary, secondary, and tertiary allylic alcohols is described using <i>tert</i>-butyl hydroperoxide as oxidant and Ti­(III) species generated by reduction of Ti­(IV) complexes, with manganese (0) in 1,4-dioxane under mild reaction conditions. The reaction proceeded with wide substrate scope and high chemo- and diastereoselectivity. A mechanistic pathway for the reaction is also discussed

The Asymmetric Total Synthesis of Cinbotolide: A Revision of the Original Structure

The structure 3,4-dihydroxy-2,4,6,8-tetramethyldec-8-enolide (<b>1</b>) was assigned to a metabolite of <i>Botrytis cinerea</i>, but the spectra of several synthetic analogues had significant differences from that of <b>1</b>. Examination of the constituents of a <i>B. cinerea</i> mutant that overproduces polyketides gave sufficient quantities of <b>1</b>, now named cinbotolide, for chemical transformations. These led to a revised γ-butyrolactone structure for the metabolite. This structure has been confirmed by an asymmetric total synthesis, which also established its absolute configuration

Phytotoxic Activity and Metabolism of <i>Botrytis cinerea</i> and Structure–Activity Relationships of Isocaryolane Derivatives

Research has been conducted on the biotransformation of (8<i>S</i>,9<i>R</i>)-isocaryolan-9-ol (<b>4a</b>) and (1<i>S</i>,2<i>S</i>,5<i>R</i>,8<i>S</i>)-8-methylene-1,4,4-trimethyltricyclo­[6.2.1.0^2,5]­undecan-12-ol (<b>5a</b>) by the fungal phytopathogen <i>Botrytis cinerea</i>. The biotransformation of compound <b>4a</b> yielded compounds <b>6</b>–<b>9</b>, while the biotransformation of compound <b>5a</b> yielded compounds <b>10</b>–<b>13</b>. The activity of compounds <b>4a</b> and <b>5a</b> against <i>B. cinerea</i> has been evaluated. (8<i>R</i>,9<i>R</i>)-Isocaryolane-8,9-diol (<b>6</b>), a major metabolite of compound <b>4a</b>, shows activity compared to its parent compound <b>4a</b>, which is inactive. The effect of isocaryolanes <b>3</b>, <b>4a</b>, and <b>5a</b>, together with their biotransformation products <b>6</b>–<b>8</b>, <b>10</b>, and <b>14</b>–<b>17</b>, on the germination and radicle and shoot growth of <i>Lactuca sativa</i> (lettuce) has also been determined. Compounds <b>7</b>–<b>13</b> are described for the first time

Chemically Induced Cryptic Sesquiterpenoids and Expression of Sesquiterpene Cyclases in <i>Botrytis cinerea</i> Revealed New Sporogenic (+)-4-<i>Epi</i>eremophil-9-en-11-ols

The sequencing of the genomes of the B05.10 and T4 strains of the fungus <i>Botrytis cinerea</i> revealed an abundance of novel biosynthetic gene clusters, the majority of which were unexpected on the basis of the previous analyses of the fermentation of these and closely related species. By systematic alteration of easy accessible cultivation parameters, using chemical induction with copper sulfate, we have found a cryptic sesquiterpenoid family with new structures related to eremophil-9-ene, which had the basic structure of the sesquiterpene (+)-5-<i>epi</i>aristolochene ((+)-4-<i>epi</i>eremophil-9-ene). An expression study of the sesquiterpene cyclase genes present in the <i>Botrytis cinerea</i> genome, under culture conditions, is reported. In general, a 3 day delay and a higher <i>BcSTC</i> genes expression were observed when copper (5 ppm) was fed to the fermentation broth. In addition, to the observed effect on the <i>BcBOT2</i> (<i>BcSTC1</i>) gene, involved in the biosynthesis of the botrydial toxin, a higher expression level for <i>BcSTC3</i> and <i>BcSTC4</i> was observed with respect to the control in the strain B05.10. Interestingly, under copper conditions, the <i>BcSTC4</i> gene was the most expressed gene in the <i>Botrytis cinerea</i> UCA992 strain. <i>In vitro</i> evaluation of the biological role of these metabolites indicates that they contributed to the conidial development in <i>B. cinerea</i> and appear to be involved in self-regulation of the production of asexual spores. Furthermore, they promoted the formation of complex appressoria or infection cushions