Remote Stereocontrol by Sulfinyl Groups: Reduction of δ-Ketosulfoxides

A highly enantioselective synthetic method towards the α2c-adrenoceptor antagonist ORM-10921

The preparation of ORM-10921, a selective α_2C-adrenoceptor antagonist with promising anti-psychotic properties, was successfully achieved using asymmetric α-alkylation of α,β-unsaturated imide and Bischler–Napieralski cyclization/asymmetric reduction as the key steps.

A general and simple diastereoselective reduction by L-Selectride: efficient synthesis of protected (4S,5S)-dihydroxy amides

A general approach to (4S,5S)-4-benzyloxy-5-hydroxy-N-(4-methoxybenzyl) amides 10 based on a diastereoselective reduction of (5S,6RS)-6-alkyl-5-benzyloxy-6-hydroxy-2-piperidinones 6 and their tautomeric ring-opened keto amides 7 is described. The reduction with l-Selectride at -20 °C to room temperature afforded the products 10 in excellent yields and moderate to high syn-diastereoselectivities.

Efficient trans-Selectivity in the Cyclocondensation of (S)-2-[2-(p-Tolylsulfinyl)phenyl]acetaldehyde with Activated Dienes Catalyzed by Yb(OTf)3

Reactions of (S)-2-[2-(p-tolylsulfinyl)phenyl]acetaldehyde 1 with Danishefsky's and related dienes took place in the presence of Yb(OTf)3 in a completely stereoselective manner, mediated by a remote sulfinyl group (1,5-asymmetric induction), to afford the corresponding 2,3-dihydro-4H-pyran-4-ones. These reactions followed a stepwise mechanism, as was corroborated by isolation of the corresponding intermediates, with a high level of trans-selectivity for 4-methyl-substituted dienes. Treatment of the adducts with Raney Ni provided concomitant cleavage of the C-S bond and reduction of the conjugated carbonyl grouping.