Pinap ligand

Quinap (95) in a number of mutually unrelated transition-metal-catalyzed asymmetric reactions.50 Thus, 105 added to tert-butyl acrylate 106 using silver acetate and PINAP ligand 96, under the conditions described in Scheme 2.25, to provide the desired product 109 in excellent enantioselectivity and yield (see Scheme 2.6 and Table 2.5). Notably, the reaction required only 3 mol% of catalyst for complete conversion at -40°C within 36 h. 

A variant of this reaction has been reported by Carreira using a novel PINAP ligand [129]. The use of 4 piperidone hydrochloride hydrate affords the tertiary amine in good yield and enantioselectivity (Scheme 1.39). The deprotection ofthe amine can... 

SCHEME 3.51 PINAP ligand in the Cu-catalyzed asymmetric A -coupling reaction. 

Although the CuBr/QUINAP system is an effective chiral catalyst in alkynylation of imines or iminiums, one drawback is that enantiopure QUINAP is quite expensive. An analog of QUINAP, PINAP (Figure 5.2), was readily synthesized and found as a very effective chiral ligand in the direct addition of alkynes to iminiums generated from aldehydes and secondary amines in situ (Scheme 5.8). ... 

A copper-catalysed, enantioselective, conjugate addition of a terminal alkyne, which undergoes an in situ metallation, has been reported. The addition of phenylacetylene to Meldrum s acid-derived acceptors (196) takes place in aqueous medium, without recourse to an inert atmosphere. The success of the enantioselective reaction was made possible by the use of PINAP (198), a new class of P,IV-ligands (cf. QUINAP), which have the advantage of easier resolution. Furthermore, these modular ligands are responsive to numerous electronic and steric modifications that permit optimization of the reaction. The products (197) were obtained in good yields and with 82-97% ee.235... 

The author expected that a reaction with a chiral ligand which coordinates to a copper atom could produce optically active 2-(aminomethyl)indoles. Knochel recently developed a novel asymmetric synthesis of chiral propargylamines with excellent ee values through a copper-catalyzed asymmetric Mannich-type reaction of alkynes with an aldehyde and a secondary amine using QUINAP as a chiral ligand (up to 98% ee) [1-3]. Carreira reported the similar synthesis of propargylic amine in up to 99% ee with PINAP [4, 5]. The author initially examined the... 

Direct enantioselective addition of terminal acetylenes to Meldrum s acid-derived acceptors promoted by Cu catalysts have been the subject of investigations by Carreira (Equation 39) [158], The process utilizes the aminophos-phine ligand N-PINAP (210), a member of a family of modular and easily synthesized QUINAP (212) analogues [159], A wide range of Meldrum s acid-derived acceptors such as 209 have been shown to participate in addition reactions of aryl acetylenes, as exemplified by the isolation of 211 in 94% yield and 95 % ee [158]. The process, in which an acetylide is generated in situ in an aqueous medium under mild conditions, owes its success to the ability of terminal acetylenes to undergo metalation in the presence of copper. 

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