BINOL regioselective substitution

Regioselective substitution reactions of a series of 2- and 3-hydroxybiaryls including BINOL have been performed via a new directed orf/io-metallation procedure.75 O-Aryl AMsopropylcarbamates, conveniently prepared from phenols and isopropyl isocyanate, have been temporarily and in situ N-protected by means of silyl inflates to form stable intermediates for low-temperature lithiation reactions using n-BuLi-TMEDA in diethyl ether. The IV,IV-dialkyl aryl O-sulfamate has been reported as a new directed metallation group.76... 

Despite efforts made to improve enantioselectivities by supporting TADDOL-titanium catalyst, the homogeneous conditions remain the best ones. BINOL was also reported as an efficient ligand, however, to our knowledge supported-BINOL-titanium complexes were not studied in the asymmetric Diels-Alder reactions. In contrast, BINOL was extensively studied in the hetero-Diels-Alder reaction and in particular in the pericyclic rearrangement of several aldehydes and electron-rich and highly regioselective Danishefslqr s diene (84) that provide access to 2-substituted-2,3-dihydro-4/f-pyran-4-ones 85 (Scheme 7.50). 

Cydoadditions. Lewis acid-mediated [3 + 2] cycloadditions of oxazoles and aldehydes or diethyl ketomalonate have been observed using organoaluminum and Sn" Lewis acids. The reactions are highly regioselective, with stereoselectivity extremely dependent upon Lewis acid (eq 32). For example, the (BINOL)AlMe-promoted reaction between benzaldehyde and the oxazole (12) provides the oxazoline with a cisitrans ratio of 98 2. The selectivity is reversed with SnCU which provides a cisitrans ratio of 15 85. frans-5-Substituted 4-alkoxycarbonyl-2-oxazolines are synthesized under thermodynamic conditions in the aldol reaction of isocyanoacetates with aldehydes. ... 

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