1,1 -Binaphthalene-2,2 -diol additives

Axially chiral guanidines with an external guanidine unit such as dinaphthoazepineamidine are effective catalysts for the enantioselective addition of p-oxoesters and a 1,3-diketone to di-ferf-butyl azodicarboxylates to yield cx-hydrazino-p-oxoesters and a-hydrazino-p-dike-tones in 54-99% yields and in 15-98% ee [44]. For example, stirring 2-oxocyclopenta-necarboxylate and di(tert-butyl) azodicarboxylate in THF in the presence of 0.05 mol% catalyst for four hours at —60° C provides an adduct in quantitative yield and in 97% ee (Scheme 4.15). The (R)-catalyst was prepared from (/ )-2,2 -dimethyl-3,3 -binaphthalene-diol ditriflate, 4-methoxyphenylboronic acid and 3.5-di(rert-butyl)phenylboronic acid in six steps. 

Various chiral crown ethers based on [1,1 -binaphthalene]-2.2 -diol, lactose or other chiral 1,2-di-ols were tested as catalyst in the addition of methyl benzcneacetate to methyl 2-propenoate using sodium amide or potassium tert-butoxide as the base. Some pertinent examples are given261 262 396. 

A diol that has proved to be an ideal bridge is the rigid chiral [l,l -binaphthalene]-2,2 -diol which is commercially available in high optical purity in both enantiomers. Furthermore, this diol can be synthesized easily in enantiomerically pure form by phenolic oxidation25, followed by a resolution of the racemic mixture25 21. In addition, a part of this valuable chiral auxiliary can be recycled after the coupling reaction. 

In a similar vein, De Lucchi and co-workers [24] prepared precursors to anti-inflammatory atrolactic acid derivatives. They used l,r-binaphthalene-2,2 -diol as an auxiliary for hydroxy aldehydes [Eq. (9)]. The symmetry of the diol ensures that only one isomer can be formed. Reaction of the diol with dibromoacelophenone produced the ketone (65 % yield). Grignard addition and hydrolysis gave only the R-hydroxyaldehyde. 

It has been previously reported that l,T-binaphthalene undergoes racemization through the triplet state,whereas this process for the 2,2 -diol derivative is proposed to involve an intermediate arising from intramolecular addition of a hydroxy group to the C2-C3 bond. Nevertheless, neither of these routes is considered to operate for the recently described efficient photoracemization of the naturally occurring l,r-biphenanthrene, blestriarene (200) in ambient light. Instead it is proposed that quinone-type species are the likely intermediates in this case. 

Binaphthalene-2,2 -diol-potassiumi Addition to imines. The heterol... 

To be accurate, the definition should be restricted to asymmetric reactions catalyzed by a combination of l,r-binaphthalene-2,2 -diol (BINOL, 4) and Ti(0 -Pr)4. Nonetheless, this chapter will give some background on non-chiral Lewis acid promoters, and include other asymmetric catalytic systems. We will not discuss the allylations that are promoted by Lewis bases, which are reviewed elsewhere, nor cover the reactions with other electrophiles. Excellent reviews already exist on "Selective Reactions Using Allylic MetaM and Catalytic Enantioselective Addition of Allylic Organometallic Reagents to Aldehydes and Ketones , as well as in the comprehensive monograph "Modern Carbonyl Chemistry. The use of BINOL-based catalysts in other fields of organic synthesis has also been reviewed. ... 

BINOL/titanium catalysts have also been reported (BINOL=l,l -binaphthalene-2,2 -diol) in the allylation of glyoxaldehyde 98. The addition of molecular sieves is extremely important for high reactivity and selectivity. ... 

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