616235-00-8

Upstream product

• 10067-33-1 (S)-(-)-p-mentha-1,8⁽¹⁰⁾-dien-9-ol 
• 5989-54-8 (-)-(S)-limonene 

Downstream Products

• 205926-46-1 C₁₀H₁₆O 
• 26462-90-8 (4S,8R)-p-menth-1-en-9-ol 

Relevant academic research and scientific papers

Stereoselective Synthesis of Limonene-Based Chiral 1,3-Amino Alcohols and Aminodiols

An unexpected ring-closing reaction of an α,β-unsaturated carboxylic acid, derived from (R)- and -(S)-limonene, in the presence of trifluoroacetic anhydride (TFAA) resulted in bicyclic α-methylene ketones and their hydroxylated analogues in a stereoselective intramolecular acylation reaction. The reaction was studied in detail, and was optimised for both compounds. The addition of secondary and primary amines to both keto alkenes followed by in-situ reduction of the resulting aminoketones with sodium borohydride gave new bicyclic terpenoid secondary and tertiary 1,3-amino alcohols and aminodiols with excellent diastereoselectivities. Regioisomeric aminodiols were prepared stereoselectively from the unsaturated 1,3-amino alcohols by hydroboration with Me2S·BH3/H2O2.

A chemoenzymatic, preparative synthesis of the isomeric forms of p-menth-1-en-9-ol: Application to the synthesis of the isomeric forms of the cooling agent 1-hydroxy-2,9-cineole

A preparative-scale synthesis of the four p-menth-1-en-9-ol isomers 2a-5a has been achieved by means of two chemoenzymatic processes. Both synthetic pathways start from the enantiomeric forms of limonene that are converted into p-mentha-1,8-dien-9-al isomers 12 and 15. The baker's yeast mediated reduction of the latter aldehydes afforded compounds 3a and 5a, respectively, with very high enantioselectivity. Moreover, chemical reduction of 12 and 15 gives the mixtures of enantiopure diastereoisomers 2a/3a and 4a/5a, respectively. PPL (Porcine pancreas lipase) mediated resolution of the latter mixtures followed by fractionating crystallization of derivatives 2b-5b allowed the enantio- and diastereoisomerically pure alcohols 2a-5a to be obtained. Compounds 2a-5a have then been used as starting materials for the preparation of four isomers of the cooling agent 1-hydroxy-2,9-cineole (6-9). Wiley-VCH Verlag GmbH & Co. KGaA, 2008.