Simple Method for the Preparation of Esters from Grignard Reagents and Alkyl 1-Imidazolecarboxylates

The reaction of Grignard reagents with alkyl imidazolecarboxylates, which were prepared from alcohols with carbonyl diimidazole, gave the corresponding esters in good to excellent yields. This method conveniently provides esters from alkyl halides and alcohols by C1-carbon chain extension

Phosphetane Oxides as Redox Cycling Catalysts in the Catalytic Wittig Reaction at Room Temperature

Recently, phosphorus redox cycling has gained significant importance for a number of transformations originally requiring the use of stoichiometric amounts of phosphorus reagents. While these methodologies have several benefits, high catalyst loadings (≥10 mol %) and harsh reaction conditions (T ≥ 100 °C) often limit their versatility and applicability. Herein, we report differently substituted phosphetane oxides as efficient catalysts for the catalytic Wittig reaction. The phosphetane scaffold is easy to modify, and a number of catalysts can be obtained in a simple two-step synthesis. The activity in the Wittig reaction significantly surpasses previously reported phospholane-based catalysts and the reaction can be conducted with catalyst loadings as low as 1.0 mol % even at room temperature. Furthermore, a Brønsted acid additive is no longer required to achieve high yields at these mild conditions. A methyl-substituted phosphetane oxide was employed to synthesize 25 different alkenes with yields of up to 97%. The methodology has a good functional group tolerance and the reaction can be performed starting with alkyl chlorides, bromides, or iodides. Additionally, it was possible to use poly­(methylhydrosiloxane) as the terminal reductant in the catalytic Wittig reaction employing 2-MeTHF as a renewable solvent. The intermediates of the Wittig reaction were analyzed by 31P NMR spectroscopy, and in situ NMR experiments confirmed phosphane oxide as the resting state of the catalyst. Further kinetic investigations revealed a striking influence of the base on the rate of phosphane oxide reduction

Organocatalytic Stereospecific Appel Reaction

Herein we report a new method for the catalytic Appel reaction by P­(III)/P­(V) redox cycling at very low catalyst loadings of 1–2 mol % using low amounts of hexachloroacetone as the halogen source and phenylsilane as the terminal reductant. Twenty-six alcohols and nine epoxides containing a wide variety of functional groups were converted to the respective chlorides and dichlorides in yields of up to 97%, enantiospecificities of up to >99%, and enantiomeric ratios of up to >99:1

Male longevity responses of four <i>Drosophila</i> species in response to four dietary treatments.

Male longevity responses of four Drosophila species in response to four dietary treatments.</p

Survival curves of <i>D</i>. <i>mel</i>. on a medium diet with and without rapamycin.

Survival curves for male and female lifespan in [days] for D. mel. on medium (2 scoops/fly/per day) diets with (blue) and without (red) rapamycin (200 μM). n = number of flies going into the analysis; escaped or flies killed by accident were discarded. (TIF)</p

Survival curves of four <i>Drosophila</i> species in response to dead Baker’s yeast.

Female and male lifespan of D. mel., D. gut., D. def., and D. tri. treated with diets including no yeast (blue), minimum dead yeast (1 scoop/fly/day, red), and minimum alive yeast (1 scoop/fly/day, green). (TIF)</p

Female longevity responses of four <i>Drosophila</i> species in response to four dietary treatments.

Female longevity responses of four Drosophila species in response to four dietary treatments.</p

Suvival curve Log-Rank results.

p-values for all compared survival curves regarding longevity are shown. (XLSX)</p

Female fecundity in response to rapamycin in four <i>Drosophila</i> species on <i>ad libitum</i> diets.

The average egg-lay response across the first ten reproductive days of D. mel., D. gut., D. def., and D. tri. on an ad libitum diet, with or without the addition of rapamycin, are shown. A) D. mel. B) D. gut. C) D. def. D) D. tri. p<0.001: ‘***’, p< 0.01 = ‘**’.</p