Heterocyclic BINAP analogues

Dr. Albert Padwa (Emory University) starts the volume with a fascinating chapter on the cycloaddition and cyclization chemistry of 2H-azirines, an area in which he has been closely connected with some of the most interesting developments. Dr. Nuzhat Arshad and Dr. Oliver Kappe of the University of Graz (Austria) update our knowledge of heterocyclic BINAP analogues, important ligands for asymmetric synthesis. 

Development of Synthetic Routes from BINAP to Heterocyclic BINAP Analogues 35... 

Several examples of heterocyclic BINAP analogues have been reported which sometimes offer an improved performance in a variety of transition-metal-catalyzed transformations when compared to standard BINAP ligands. In this review, we survey the efforts of developing atropisomeric biheteroaryl backbone-containing bisphosphines, their designing concept, synthetic approaches and some of their important applications. 

DEVELOPMENT OF SYNTHETIC ROUTES FROM BINAP TO HETEROCYCLIC BINAP ANALOGUES... 

Scheme 4 General synthetic scheme for heterocyclic BINAP analogues.

Since the diphosphine is appreciably more electron-rich than is BINAP, the major ruthenium complex is a more active hydrogenation catalyst than the parent. Increased electron-rich ligation may be the reason for the success of heterocyclic analogues of BINAP in which the binaphthalene is replaced by a bi(ben-zothiophene) or biindolyl the resulting Ru complexes are effective both in terms of enantioselectivity and reactivity [139]. Readers of the related Chapter 6.1 on the asymmetric hydrogenation of carbonyl compounds will encounter the Ru complexes of ligands in the DUPHOS family, where the ease of modification of the alkyl substituents of the phospholane enhances the power of the system, since it permits the easy optimization of ee for any substrate [140]. 

Heterocyclic analogues of BINAP, such a< 2,2, 5,5 -tetramethyl-4,4 -bis(dipheny Iphosph and tested in the Heck reaction. Incorporaut sulfinyl group to a double bond elicits enj intramolecular Heck reaction. Optically ai ides are produced from (/ )-l-f-butylsulfinylcy Palladacycle (109) and its analogues ind rearrangement of allylic imidates. - For a thioamides, it is convenient to allylate thi dine. This process involves a thio-Claisen n Enantioselective deprotonation of ketones slum bis[yV-benzyl-N-(a-phenethyl)]amide.-- tonation of enolates. ... 

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