Sagami-synthesis

According to the Sagami synthesis, prenol is reacted with methyl orthoacetate. A Claisen rearrangement yields methyl 3,3-dimethylpent-4-enoate, which undergoes a radical addition to tetrachloromethane. The double elimination of hydrogen chloride gives finally permethric acid. In this transformation, the base and the solvent have a critical impact on the cis/trans-ratio. Under the most favourable conditions (t-BuONa, hexane, HMPT) the cis-proportion can reach up to 90%. [102-104]... 

An adapted version of the Sagami-synthesis (Reaction scheme 65) allows the use of the interesting 3,3-dimethylpentenic ester IIL If one chlorine atom in carbonte-trachloride is substituted by CF3 or CH3, or if 1,1-dibromotetrafluoroethane is used, the radical addition to this olefinic bond is still feasible. As in the case of 1,1,1-trichloroethane, more drastic conditions are required. l,l,l-trichloro-2-tri-fluoroethane, on the other hand, behaves almost normally, thus providing an efficient starting point to produce the desired acid as shown in Reaction scheme 144, particularly if the 1,3-cyclo-elimination is carried out with potassium carbonate in dimethylacetamide at 140 °C, giving predominantly the cis-Z-isomer [411]. 

Diazoester synthesis [431] is less interesting. Elements of the strategy of the Sagami-synthesis can be applied [432, 433] as shown in Reaction scheme 149. 

The Sagami-synthesis, starting with a meta-phenoxyphenyl ester of 3,3-dimethyl-pentenoic ester (Reaction scheme 263) gives permethrin 372, without having to go through the step of free permethric acid [181]. 

The [2 + 2]-cycloaddition reaction was used to explore synthetic routes toward key intermediates that could be applied in carbapenem antiobiotic synthesis and in the preparation of such intermediates, chemists at the Sagami Research Institute utilized the Corey-Kim reaction.8 In this example, secondary alcohol 32 was converted to ketone 33 in 95% yield. 

Immediately after the discovery of the advantageous properties of permethric acid, many research laboratories initiated enhanced efforts to find the most convenient synthesis ofthis compound. The Japanese Sagami Research Institute developed a synthetic route based on a Claisen rearrangement and a 1,3-cyclo-elimination, for which FMC took out a licence. A few weeks later, two other firms, Sankyo and Kmaray, filed patent applications for similar syntheses. 

Catalysts for ammonia synthesis consisting of graphite complexes, especially those containing ferric chloride and potassium. (Sagami Chemical Research Center). DE 2114769 (1971). 

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