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A nonracemic bicyclic lactam has been used to construct a chiral cyclopentane containing vicinal quaternary carbon centers in optically pure form, which is common to all of the title compounds. An oxazoline-mediated asymmetric Ullmann coupling was then utilized to establish chirality about the biaryl axis of mastigophorenes A and B. Through the course of this synthesis, it was clearly demonstrated that smaller chiral auxiliaries lead to higher levels of atroposelection, a previously unknown phenomenon of the asymmetric Ullmann coupling.

The use of chiral bicyclic lactams, in their thiocarbonyl form 9, has been shown to serve as important intermediates for producing α-quaternary alkyl derivatives 8, which were readily transformed into the title compound (−)-1. The reversibility of the thio-Claisen rearrangement, 15⇌8, was clearly demonstrated and appears to be unprecedented. Solvent effects to alter the equilibrium position were studied and found to have only a moderate, but beneficial effect. The title compound was obtained in 14% overall yield in 10 steps from bicyclic lactam, 9.

Cis- and trans-decahydroquinolines, as their t-Boc and formamidine derivatives, have been metalated and alkylated. The former gives mainly axial alkylation whereas the latter gives equatorial alkylation in the trans series. For the cis series, the t-Boc derivative gives essentially pure equatorial alkylation as does the formamidine derivative. Several electron-transfer processes occur simultaneously with the ionic alkylation, and this can be altered by use of pentynylcopper or HMPA. Furthermore, cuprates, when employed, gave good yields of alkylation product via radical pathways, but the stereochemistry suffered. A synthesis of the poison dart frog secretion, pumiliotoxin C, has been accomplished using these alkylation techniques

The asymmetric synthesis of (S)-(+)-cryptaustoline was accomplished and found to differ in sign of rotation with the natural «S»-(-)-material. The previously assigned absolute configuration was found to be incorrect and is now corrected. The reversal in stereochemistry came about through an unusual manner involving (S)-(+)-laudanosoline (3) cyclizing to (R)-(-)-cryptaustoline ((-)-1c). The mechanism was explored by oxidation of a series of deuterio derivatives of laudanosoline, all of which retained deuterium in the resultant cryptaustoline

The oxazoline-mediated biaryl coupling reaction was applied successfully to the total synthesis of a series of dibenzocyclooctadiene lignans in chiral nonracemic form. The diastereoselectivities achieved in the coupling reaction varied in a predictable manner, primarily as a function of the ortho substituents on the phenyl Grignard reagent

The natural alkaloid cryptaustoline is (13R,7S)-(−)-1 due to the heretofore unprecedented inversion while the formamidine route led to the expected (13S,7R)-(+)-1

Description d'une procedure generale pour la synthese de biphenyles chiraux via substitution aromatique nucleophile d'un groupe o-methoxy par un reactif de Grignard aromatique avec une oxazoline en tant qu'auxiliaire chiral. Determination des vitesses de racemisation des biphenyles

L'addition successive d'alkyllithium et d'iodomethane a des (methoxymethyl-4 [naphtyl-1 et 2]-2 phenyl-5) oxazolines-2 donne des [alkyl-2 dihydro-1,2 methyl-1 naphtyl-1]-2- et [alkyl-1 dihydro-1,2 methyl-2 naphtyl-2]-2 methoxymethyl-4 phenyl-5 oxazolines-2

Le ([dimethyl-4,4 oxazoline-2yl-2]-3) benzyne genere par lithiation de la (chloro-2' phenyl-2 dimethyl-4,4) oxazoline-2, permet d'acceder a des derives polysubstitues du benzene tres varies

Les lactames bicycliques chiraux derives de l'oxa-4 aza-1 bicyclo [3.3.0] octanone-8 sont des precurseurs tres utiles de centres carbones quaternaires generes avec une enantioselectivite elevee