Cationic palladium(ii) complex-catalyzed [2 + 2] cycloaddition and tandem cycloaddition–allylic rearrangement of ketene with aldehydes: an improved synthesis of sorbic acid
Cationic palladium(II) complexes [PdL2(PhCN)2](BF4)2 efficiently catalyze the [2 + 2] cycloaddition of ketene with aldehydes to give the corresponding oxetan-2-ones, among which 4-vinyl-substituted ones are further isomerized under the conditions to give 3,6-dihydro-2H-pyran-2-ones in good yields.
Synthesis of 3,6-dihydro-2H-pyran-2-ones via cationic palladium(II) complex-catalyzed tandem [2+2] cycloaddition-allylic rearrangement of ketene with α,β-unsaturated aldehydes and ketones
Treatment of ketene with α,β-unsaturated aldehydes and ketones in the presence of [Pd(dppb)(PhCN)2](BF4)2 leads to the formation of 4-vinyloxetan-2-ones, which rearrange under the conditions to give 3,6-dihydro-2H-pyran-2-ones in a variety of yields, depending on the substituents. Asymmetric induction with up to 57% de has been achieved by using α,β-unsaturated aldehydes bearing an asymmetric carbon
The invention provides an agrochemical composition comprising: (a) one or more fatty acids or derivatives thereof; and (b) a strain, culture, culture filtrate, spores or mycelia of a species of a fungus or oomycete, or a metabolite produced by a species of a fungus or oomycete, which strain, culture, culture filtrate, spores, mycelia or metabolite directly or indirectly (i) inhibits the growth or reproduction of plant pathogens or (ii) kills plant pathogens. Also provided is a method for controlling fungi or oomycetes at a locus, a method for promoting growth in a plant and a method for controlling nematodes at a locus.