Tolpyralate, a new selective postemergence herbicide developed for the weed control in corn, possesses a unique chemical structure with a 1-alkoxyethyl methyl carbonate group on the N-ethyl pyrazole moiety. This compound shows high herbicidal activity against many weed species, including glyphosate-resistant Amaranthus tuberculatus. Tolpyralate targets 4-hydroxyphenylpyruvate dioxygenase (4-HPPD), which is involved in the tyrosine degradation pathway. Inhibition of the enzyme destroys the chlorophyll, thereby killing the susceptible weeds. Details of tolpyralate discovery, structure optimization, and biological activities are described.

Base-catalyzed condensation of 1,2-bis[5-tert-butyl-3-(5-tertbutylsalicyl)-2-hydroxyphenyl]ethane (8) with formaldehyde in xylene affords a novel ethylene-bridged calixarene-analogous macrocyclic metacyclophane. However, not the desired 2 has been obtained. Instead, the novel macrocyclic cornpounds pentahydroxy[2.1.2.1.1]-(9) and hexahydroxy-[2.l.l.l.l.l]metacyclophane (10) have been isolated in 35 and 25% yields, respectively. The mechanism for the above disproportionation occurring during the base-catalyzed condensation of 8 to afford these macrocyclic metacyclophanes and their 'H-NMR spectral behavior are discussed.Extensive studies of calixarenes have been carried out during the last decade"]. Calixarenes are readily obtained by base-induced condensation of p-substituted phenols with demonstrating that the aromatic rings are invariably connected by methylene bridges. Their phenolic hydroxyl groups are ordered in well-shaped cyclic arrays due to strong intramolecular hydrogen b o n d~ [~-~] .In view of this fact it seems to be surprising that there are very few reports on the preparation of calixarenes containing bridges other than methylene units and on the characterization of their hydrogen bonding17-' ' 1.Recently, we have found a convenient synthesis of ethylene-bridged calixarene-analogous metacyclophanes 4 involving base-catalyzed condensation of 1,2-bis(5-tert-butylxylene, which discloses the unique properties of these compounds[' l]. They contain methylene and ethylene bridges in a ratio of 1 : 1. 2-hydroxypheny1)ethane (3) with formaldehyde in refluxing 1This strategy is supposed to be employed for the preparation of octahydroxy[2.1.1.1.2.1.l.l]metacyclophane 2 and its analogues by using the same condensation reaction of 1,2-bis[5-tert-butyl-3-(5-tert-butylsalicy1)-2-hydroxyphenyl]-ethane (8) with formaldehyde. Since the intramolecular hydrogen bonding between the hydroxyl groups of the diarylmethane units may be stronger than that between the hydroxy groups of the diarylethane units, the formation of a 1 : 2 complex of 8 with alkali metal ion may be possible in a "pleated loop" conformation like calix [8]arene l r 4 3 1 2 ] .In this paper, we report on the preparation and conformational properties of novel ethylene-bridged calixareneanalogous macrocyclic metacyclophanes 9 and 10.

The preparation of a novel macrocyclic compound, tetrahydroxy[3.1.3.l]metacyclophane 5 by base-catalysed condensation of 1,3-(2,2'-di hydroxy-5,5'-di-tert-butyldiphenyl) propane 4 with formaldehyde in xylene in 90% yield is described and its conformational properties are discussed.

A convenient preparation of diphenylmethanes such as (III) using cross coupling reaction of the benzyl chlorides (I) with the Grignard reagents in the presence of CuBr as catalyst (II) is described.