Abstract
A series of pyrimidinyl benzylamine analogues containing a phosphonyl group (2) was synthesized via the Mannichβtype reactions of 2β(4,6βdimethoxypyrimidinβ2βyloxy)benzoaldehyde 1, aromatic amines, and dialkyl phosphites or triphenyl phosphite in the presence of Mg(ClO~4~)~2~. Their structures were characterized by spectroscopic data (infrared, ^1^H NMR, ^31^P NMR, and mass spectrometry) and elemental analyses, and compound 2b was further determined by Xβray diffraction crystallography. The results of preliminary bioassays (in vitro) showed that most of title compounds 2 exhibited higher herbicidal activities against dicotyledonous weeds (Brassica campestris L.) than monocotyledonous weeds (Echinochloa crusβgalli). Further bioassays (in vivo) indicated that some of 2 displayed as good herbicidal activity against amaranth pigweed (Amaranthus retroflexus) as the commercially available herbicide, Bispyribacβsodium, in both preemergence and postemergence treatments at the dose of 1.5 kg/ha. Β© 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:148β155, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20589