Vitex rotundifolia, mosquito repellent

In 1995 Watanabe et ol. at Sumitomo Chemical Co. isolated and identified a degraded monoterpenoid (+)-rotundial (68, Figure 3.17) as a new mosquito repellent from Vitex rotundifolia, a medicinal plant whose leaves and twigs were used for repelling mosquitoes. They reported that the mosquito-repelling activity... 

C9H12O2, Mr 152.19, oil, [0] +39.3° (CHCI3). A dialdehyde from the leaves of Vitex rotundifolia, Verben-aceae, with insecticidal activity. The leaves are traditionally used in Japan as a mosquito repellant. R. has the same activity against Ae[Pg.559]

In 2009, the Christmann group reported the application of a dienamine intermediate for Rauhut-Currier-type reactions (775). In this case, the a-position of the dienamine acts as the nucleophile in an intramolecular cyclization reaction giving access to functionalized monocyclic compounds. The applicability of this strategy was illustrated in the synthesis of (7 )-rotundial (193), a mosquito repellent from the leaves of Vitex rotundifolia (175). Hence, an organocatalytic Rauhut-Currier-type reaction of dialdehyde 192 catalyzed by 20 mol% (5)-138 gave (7 )-rotundial (193) directly in good enantioselectivity, albeit in only a moderate yield (Scheme 46). 

Watanabe K, Takada Y, Matsuo N, Nishimitra H (1995) Rotrmdial, a New Natural Mosquito Repellent from the Leaves of Vitex rotundifolia. Biosci Biotechnol Biochem 59 1979... 

The group led by Christmann exploited this property for the synthesis of rotundial, a mosquito repellent isolated from Vitex rotundifolia (Scheme 11.27). Using catalyst 12, the dienamine was formed on the most hindered enal. Intramolecular addition of the dienamine to the enal and subsequent isomerization of the double bond to the more stable conjugated one affords rotundial in a relatively modest 36% yield and 86% ee. 

---

See also in sourсe #XX -- [ ]

---