A new route for synthesis of 3,6-dialkyl-1,4-dimethyl-3,6-epithio- (8) and -3,6-epidithio-2,5-piperazinediones (9) via the corresponding bromo derivatives was described. Bromination of 3,6-dialkyl-1,4-dimethyl-2,5-piper-azinedione with N-bromosuccinimide gave 3,3α,6,6α-tetrabromo (2) and 3,6-dibromo (3) derivatives, depending upon the straight chain (methyl, ethyl, propyl, butyl) or α-branched (isopropyl, sec-butyl) alkyl groups, respectively. After tentative substitution of 3,6-bromine atoms of 2 with methanol, 3α,6α-bromine atoms were reduced to give the corresponding 3,6-dialkyl-3,6-dimethoxy derivatives (5). Substitution of 3 or 5 with hydrogen sulfide in the absence or presence of zinc chloride, and successive oxidation with potassium triiodide gave 8 and 9 at the same time. Discussions were made on the structure of isomers and on the reaction mechanisms.

This paper reports the synthesis of novel N-alkyl-N-(substituted benzyl)-4-halo-2-alkenamides and their herbicidal activity against Echinochloa oryzicola. Their herbicidal activity was observed to be light-dependent. The study on the structure-activity relationships revealed that 4-chloro-2-pentenoyl is the best as the acyl skeleton, and the combinations of either isobutyl or isopentyl and either 4-cyano-or 4-chlorobenzyl substituents on the amide nitrogen atom are the most favorable to the activity.

The N-isobutyl-N-(4-substituted benzyl)-4-halo-2-pentenamides show a potent light-dependent herbicidal activity against the barnyard grasses. The herbicidal mechanism was investigated with assay systems using cotton seedlings and an enzyme preparation from them as well as cultured unicelluar microalgae. Besides the protoporphyrinogen oxidase inhibition, some other mechanism(s) inhibiting step(s) involved in the chlorophyll biosynthetic pathway were suggested as the origin of the phytotoxicity.

Abstract-The in vitro and in vivo effects of the newly synthesized compound 6,thiazole 2-carboxamide) on immune responses were investigated in comparison with that of levamisole (LMS). TOK-8801 enhanced the anti-sheep red blood cells (SRBC) plaque forming cells (PFC) response and mitogen-induced proliferative responses in murine splenocytes and thymocytes in vitro at concentrations of 10-7-10-5 M, while LMS augmented these responses at 10-4M. The stimulatory effect of TOK-8801 as well as LMS on the antibody production was eliminated by the removal of T cells. TOK-8801 (0.5 mg/kg, p.o.) suppressed the in vivo generation of anti-SRBC PFC in normal mice, but the compound restored the depressed antibody production in restraint-stress mice which was mainly caused by helper T cell defects. From these results, TOK-8801 was shown to have an immunomodulatory activity in the an tibody production.

The thirty-four N-methyl-2)-methoxy(substituted)benzanilides were synthesized and their preventive activities against rice blast were studied by the pot test. The substitution at the para-position of benzoyl moiety varied the activity to various extents.The inhibitory activity of N-methyl-2)-methoxy-4-substituted benzanilides on the penetration of infection pegs from appressoria of Pyricularia oryzae were also measured by using cellophane film as a model of plant cell walls and the structure-activity relationships were analyzed using the physicochemical parameters and regression analysis. The inhibitory activities were related to the bulkiness and electronic effect of the substituents and parabolically to the hydrophobicity of the molecules.