What is proposed are specific tetrahydrofuran derivatives of the formula (I), fragrance and aroma substance mixtures comprising these tetrahydrofuran derivatives, their use in fragrance or aroma substance (mixture) and corresponding perfumed products.
What is proposed are specific tetrahydrofuran derivatives of the formula (I), fragrance and aroma substance mixtures comprising these tetrahydrofuran derivatives, their use in fragrance or aroma substance (mixture) and corresponding perfumed products.
To develop a practical scalable approach to (R)-tetrahydrofuran-2-carboxylic acid (THFC) 1, a chiral building block for furopenem. 2, enantioselective hydrolysis of its esters is explored: When ethyl (+/-)-tetrahydrofuran-2-carboxylate 3d (2 M, 288 g/L) is digested by an Aspergillus melleus protease 0.2% (w/v)} in a 1.5 M potassium phosphate buffer (pH 8) for 20 h, enantioselective hydrolysis proceeds with E=60 to give (R)-THFC 1 in 94.4% ee. On separation from the left-over antipodal ester (S)-3d by partition, (R)-THFC 1 is treated with N,N-dicyclohexylamine (DCHA) in methyl ethyl ketone/methanol (5:1) to precipitate the crystalline salt 4 that contains (R)-THFC 1 of >99% ee in 22% overall yield from (+/-)-3d. (C) 2003 Elsevier Science Ltd. All rights reserved.