Ji-Facial selection

The orbital mixing rules are described in detail and shown to be powerful for understanding and designing selective reactions in Chapter Orbital Mixing Rules and applied in chapter ji-Facial Selectivities of Diels-Alder reactions . 

The ji-facial selectivity of the asymmetric Diels-Alder reaction of 2,4-dipheiiyl-l-thiabuta-1,3-diene 140 with the chiral (5)-/V-acryloyl-4-benzyloxazolidin-2-one 141 can be controlled by solvents or additives. For instance, in dichloromethane in the absence of Lewis acids, a 79 21 mixture of eiido and e.xo isomers is obtained with 67% diastereoisomeric excess of the (35, 45)-c/ t/o-isomer 142 in contrast, in dichloromethane in the presence of ytterbium(III) triflate, 84— 99% de of the (3/ , 4/ )-isomer 143 is produced <97TL3231>. 

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