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The diastereoselectivity of adducts in the addition reaction via the Felkin-Anh model is affected significantly by the steric effect of bulky groups. However, the influence of steric alkyl chain length has not been studied for the diastereoselectivity. In this work, we present a new strategy for the racemic synthesis of β-methyl alcohols to obtain various diastereomer ratios using the Felkin-Anh model. The addition of alkyl Grignard reagents to α-methyl aldehydes afforded diastereomer ratios of threo/erythro ≈ 2:1, while the reduction in structurally related ketones using LiAlH4 afforded ratios of threo/erythro ≈ 1:1. The experimental data showed no effect of alkyl chain length on either side on the stereoselectivity of adducts. All synthesized analogues were evaluated for attractiveness to Rhynchophorus ferrugineus weevils in the field. Five novel derivatives, including two alcohols and three ketones, were found to attract weevils in the field trials. Among them, 3-methyldecan-4-one (5b) and 4-methyldecan-5-ol (11a) were found to be the most attractive to the insects.

Nguyen HU, Phan QN, Dang HT, Son TTN, Nguyen HN, Nguyen THT. 2021. Morphology, biology, and damage behaviors of nutsedge borer (Bactra venosana Zeller) in Tra Vinh Province, Vietnam. Biodiversitas 23: 733-741. Nutsedge borer, Bactra venosana Zeller (Lepidoptera: Tortricidae), is a common pest of sedge in Tra Vinh Province. To control this species, its morphology, biology, and behaviors were investigated in Tra Vinh Province. The study was conducted with the aim of determining the information related to the Bactra venosana, as a basis for developing a strategy to manage this species by means of safety solutions. The study was carried out by surveying the behavior of nutsedge borer in sedge fields and determining their morphological and biological characteristics under laboratory conditions. The results showed that the eggs were 1.06 ± 0.17 mm (in length), 0.84 ± 0.16 (in width), oval, and white after turning pale yellow. Larvae progressed through 5 instars with body length and width of 1.20 ± 0.18 mm to 11.3 ± 1.23 mm and from 0.25 ± 0.05 to 1.05 ± 0.25 mm, respectively. Newly hatched larvae were dark yellow, and pupae were pale green. The male pupa was 7.75 ± 0.68 mm long, while the female was 8.46 ± 0.93 mm long, light green, and dark brown about to mature. The male adult of B. venosana was usually gray-brown and 7.70 ± 0.60 mm in body length, whereas the female adult was silver-gray, 8.41 ± 0.86 mm. The life cycle passed 35.9 ± 2.55 days in laboratory conditions. Under field conditions, eggs were laid scattered on the surface of the host plants. Larvae bored inside the stems of sedge. Newly damaged sedge plants had no symptoms at first whose bodies got soft, turned from light green to pale yellow, and gradually wilted and died.