1,1,2-Trisubstituted dihydronaphthalenes

Generation in situ.1 A synthesis (12, 310-311) of 1,1,2-trisubstituted dihydronaphthalenes (3) involves as the first step addition of alkyllithiums to the 1-naphthyloxazoline 1 followed by trapping with an electrophile. The products (2) can be converted to formyl-1,2-dihydronaphthalenes (equation I). Addition of RLi... 

The methodology was extended to an asymmetric introduction of snbstitnents to a naphthalene ring. When chiral naphthyloxazolines 13 were used as substrates, di- or trisubstituted dihydronaphthalenes 15 were obtained in high diastereomeric ratio (dr) after the treatment of intermediate azaenolate 14 with an electrophile (equation 7) °. Analogous reactions with a chiral naphthaldehyde imine were also reported . 

The BHA group exerts remarkable activating and directing effects on the reaction of naphthalenecarboxylates with organoiithium reagents [24,25]. In the presence of either stoichiometric or catalytic amounts of the chiral diether 18, aryllithiums reacted with BHA esters of 1- and 2-naphthalenecarboxylic acid 21/22 to afford 1,2-di-, 1,1,2- and 1,2,2-trisubstituted dihydronaphthalenes 23/24 in high ee, following a subsequent ketene-reduction in a one-pot process (Scheme 7). 

Trisubstituted alkenes (1,2-diphenylpropene, 1-methyl-3,4-dihydronaphthalene) have been hydrogenated with excellent optical yields (83-99% ee) in the presence of a chiral bis(tetrahydroindenyl)titanocene catalyst.159... 

The reaction rate of the addition decreased on going from phenyl-substituted alkenes to mono-, di-, and trisubstituted alkenes. A preference for E double bonds over Z double bonds was exhibited by the monoimido complex 1. Complete regioselectivity was observed with mono-and trisubstituted alkenes and gmi-disubstituted alkenes, since the C-N bond is formed exclusively at the least substituted alkene carbon, for example of 1-methyl- and 1-phenylcyclo-hexene. However, for 1,2-disubstituted alkenes the regioselectivity depended on the substrate70,71. Unexpectedly, benzylic amination was predominant in the reaction mixtures derived from 1-phenylpropenes and 1,2-dihydronaphthalene (Tabic 5). 

Using Upjohn condition (OsOi-NMO). The utility of the Upjohn protocol for the dihydroxylation was recently demonstrated in the synthesis of bicyclic analogues of pentopyranoses, (-)-anisomycin, trisubstituted y-butyrolactone, 6-bromo-4-(l,2-dihydroxyethyl)-7-hydroxycoumarine (Bhc-diol) as a photoremovable protecting group, 3,4-dihydroxy-2-(3-methylbut-2-enyl)-3,4-dihydronaphthalen-l(2//)-one, benzo-[c]pyrano[3,2-/z]acridin-7-ones, both enantiomers of conduri-tol C tetraacetate and of mei o-conduritol-D-tetraacetate. ... 

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