Asymmetric synthesis matched double

Review on matched and mismatched pairing in double asymmetric synthesis Masamune, S, Choy, W. Petersen, J.S. Sita, L. R., Angew. Chem., Int. Ed. Engl., 1985, 1-30. 

The synthesis commenced with the matched double asymmetric reaction of the (/ ,i )-prenylboronate 238 (synthesized from 3-methyl-1-butene in a manner analogous to the preparation of crotylboronates 219 and 213) with D-glyceraldehyde pentylidene ketal 259, forming adduct 260 with >99 1 diastereoselectivity... 

From the many examples of reactions with imines activated in various ways, we select the asymmetric synthesis of pipecolic acids by double diastereomeric induction using an activated imine 87 with two chiral auxiliaries - a-methylbenzylamine on the nitrogen atom and 8-phenylmenthol as esterifying group. Both these auxiliaries were discussed in earlier chapters (22 and 27). Acid-catalysed cycloaddition with normal dienes gives excellent asymmetric induction and reasonable yield. We show the matched case - the mismatched case is obviously worse.13... 

When two of the reaction components are chiral (any combination of substrate, reagent, catalyst, or solvent), the chirality elements of each reactant will operate either in concert (matched pair) or in opposition (mismatched pair) and together influence the stereochemical outcome of the reaction. In this case, the reaction is subject to double asymmetric induction. Unless the diastereofadal selectivities of both chiral reactants are in opposition and identical in magnitude, the ratio C D 1. Applications of double asymmetric induction in synthesis will be discussed in Chapter 5. 

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