Quaternary stereocenters are obtained at room temperature in copper-catalyzed asymmetric Michael reactions with α-amino acid amides as chiral auxiliaries. L-Valine diethylamide was applied as a chiral auxiliary, and an optically active piperidine derivative was prepared with 97% ee. The

Scaffold: Perfect Felkin-Anh Diastereoselectivity. -The first optically active decahydro-6-isoquinolone derivative (II) with a quaternary stereocenter is synthesized. The racemic aldehyde reacts with a number of different Grignard reagents to give the secondary alcohols in good yields as single diastereomers. High diastereoselectivity for the addition of nucleophiles to carbaldehyde groups in a neopentyl environment has not been reported so far. -(CHRISTOFFERS*, J.; SCHARL, H.; FREY, W.; BARO, A.; Org. Lett. 6 (2004) 7, 1171-1173; Inst. Org. Chem., Univ. Stuttgart, D-70569 Stuttgart, Germany; Eng.) -Steudel 33-164

Diastereomerically and enantiomerically pure decahydro-6-isoquinolone derivative 7 (>99% de, 97% ee) was obtained from the Michael addition product 3. Interestingly, aldehyde 7 reacted with a number of different Grignard reagents to give the secondary alcohols 9 in good yields as single diastereomers. This result can be explained by taking the Felkin-Anh model into account.

A straightforward synthesis of optically active decahydro‐6‐isoquinolone derivative 3, containing a quaternary stereocenter, is reported. The starting (R)‐configured enantiopure enone 2, which is readily accessible through a copper‐catalyzed, L‐valine amide mediated Michael reaction and a subsequent Robinson annulation, was hydrogenated with Pd/C in iPrOH to give the decahydroisoquinolone 4. Treatment of 4 with ethyleneglycol in the presence of PPTS yielded the dioxolane‐protected derivative 7. A sequence of ester reduction with LiAlH4 and subsequent Ley oxidation of the resulting primary alcohol 10 accomplished the synthesis. Enantiomerically pure aldehyde 3, with three groups for further functionalization, was thus obtained in 63% overall yield. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

An improved procedure for the stereoselective synthesis of axially chiral biaryl systems is described, by atroposelective ring cleavage of configurationally unstable lactone-bridged biaryls with amino acid esters as inexpensive and efficient chiral N-nucleophiles. Starting with configurationally unstable lactones of type 2, which are readily accessible by intramolecular Heck reaction of the respective bromo esters 1, the atroposelective ring cleavage succeeds by using a broad variety of amino acid esters of type 5, leading to configuratively stable axially chiral biaryl amides 3 in good chemical yields and excellent diastereomeric ratios of up to Ͼ 99.5:0.5.