*2.1. Lipid Alcohols*

C19 Lipid Diols

Diastereomeric *trans*-oxylipids **1**, and *cis*-oxylipid **2** (Figure 3), were isolated in 1980 [21] and 1998 [22], respectively, from the brown alga *Notheia anomala*. Their structure and relative stereochemistry were assigned by 1D and 2D NMR spectral data and confirmed by single-crystal X-ray analysis. Their absolute configuration was determined by the Horeau method in the case of compound **1**, and by the advanced Mosher method for compound **2**. Both of them display in vitro antihelmintic activity, inhibiting larval development in parasitic nematodes. The *trans*-isomer **1** showed LD50 values against *Haemonchus contortus* (1.8 ppm) and *Trichostrongylus colubriformis* (9.9 ppm), comparable to those of the commercial nematocides levamisole and closantel. Synthetic routes for these oxylipids were recently reviewed [18].

**Figure 3.** Structure of *trans*-oxylipid **1** and *cis*-oxylipid **2**.

An elegant example of the stereodivergent synthesis of both isomers was developed by Kim et al. [23]. They developed an intramolecular amide enolate alkylation, where the C3-hydroxy protecting group selection permits the formation of the desired isomer (Scheme 1). Thus, starting from PMB-protected bromoamide **3**, reaction with LiHMDS afforded only the *cis*-product **4**. The preferent formation of the *cis*-isomer was due to the chelating ability of the PMB group. Therefore, when using a nonchelating group such as TIPS (compound **5**), the reaction with KHMDS predominantly yielded the *trans*-THF **6**. Further reaction of **4** and **6** with CH2=CH(CH2)7MgBr and reduction with L-selectride afforded **7** and **8** in good yields (76% and 53% over two steps, respectively). Deprotection of **7** with DDQ, and **8** with TBAF, respectively, gave *cis*-oxylipid **2** in 82% yield and the *trans*-isomer **1** in 94% yield.

## *2.2. Fatty Acids*
