SPINOL-phosphoric acids catalysts

An enantioselective synthesis of dibenzo[l,4]diazepines 81 has been realized by employing a SPINOL-derived chiral phosphoric acid catalyst 82 in a three-component reaction between 1,2-phenylenediamines 78, aryl aldehydes 80 and cyclohexane-1,3-diones 79 (14ASC2009).The reaction was generally high yielding and enantiomeric excesses up to 88% could be obtained, although in general the enantioselectivity was moderate. 

Spirocyclic phosphoric acid catalyst STRIP (6) turned out to be crucial in the development of the kinetic resolution of homoaldols. The SPINOL backbone outperformed a variety of other previously described phosphoric acids based on BINOL (3 and 2), H8-B1NOL (9), VAPOL (1), and TADDOL (10) backbones (Table 2). 

An organocatalytic, enantioselective version of this reaction was reported in 2013 by Lin s group, which was based on the use of a chiral SPINOL-phosphoric acid derivative 35 as catalyst (Figure 3.3) [28]. This process proceeds in moderate to good yields (39-65%) and in very good diastereo (dr up to 20 1) and enantioselectivities (ee up to 99%). 

Xu and co-workers [20] reported the use of SPINOL-phosphoric acid (CAT-10) to catalyze an enantioselective version of the Biginelli reaction (Table 2). These authors evaluated six chiral catalysts that had different substituents... 

Moreover, the unique structural properties of spirocyclic compounds inspired the design of new ligands and catalysts such as spirobisoxazolines (8), SPINOL (9), SPRIX (10), SPINOL-derived phosphoric acids (11), and spirOP (12) with excellent catalytic activities (Figure 10.2) [2]. 

The SPINOL-based phosphoric acid (157) has been found to be a general, highly enantioselective catalyst for asymmetric allylboration of aldehydes with pinacol allylboronates (156). Excellent enantioselectivities have been obtained for different types of aldehydes including aromatic... 

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