Crystal structures of two 1,2,3,4-tetrahydronaphthalenes obtained during efforts towards the total synthesis of elisabethin A

The two substituted 1,2,3,4-tetrahydronaphthalenes, methyl ( R )-3-{(1 R ,4 S )-6-methoxy-4,7-dimethyl-5,8-bis[(triisopropylsilyl)oxy]-1,2,3,4-tetrahydronaphthalen-1-yl}butanoate, C 36 H 66 O 5 Si 2 , ( 2 ), and methyl ( E )-3-{(1 R ,4 S )-8-hydroxy-6-methoxy-4,7-dimethyl-5-[(triisopropylsilyl)oxy]-1,2,3,4-tetrahydronaphthalen-1-yl}acrylate, C 26 H 42 O 5 Si, ( 8 ), crystallize in the Sohncke space groups P 2 1 2 1 2 1 and P 2 1 , respectively, with the absolute structure determined on the basis of anomalous dispersion effects. The configurations of the stereo centres in the 1,2,3,4-tetrahydronaphthalene moiety of ( 2 ) and ( 8 ) are the same, and the conformation of the non-aromatic part of the ring system is nearly identical. In the crystal of ( 2 ), weak non-classical C—H...O interactions consolidate the packing, whereas in ( 8 ), intermolecular O—H...O hydrogen-bonding interactions of medium-to-weak strength direct the molecules into Z -shaped strands extending parallel to [010].