Oxazoline N-Oxide-Mediated [2 + 3] Cycloadditions: Application to a Total Synthesis of the Hypocholesterolemic Agent 1233A

Abstract

Oxetanone 1233A 1 has been synthesized in 22 steps and 3.43% overall yield from 3-methylglutaric anhydride. Asymmetric carbon at C7 was introduced by a diastereoselective esterification of 3-methylglutaric anhydride, whereas the two asymmetric carbons at C2 ‘ and C3 ‘ were controlled by an asymmetric [2 + 3] cycloaddition using camphor-derived oxazoline N-oxide as dipole.

A Ring Closing Metathesis Approach to the Formal Synthesis of (+)‐Callyspongiolide

“…R f 0.31 (petroleum ether/Et 2 O, 1 : 1); −5.0 ( c 0.10, CHCl 3 ); 1 H NMR (400 MHz, CDCl 3 ) δ 3.77–3.67 (m, 2H), 2.24–2.12 (m, 2H), 1.98 (t, J =2.7 Hz, 1H), 1.93–1.82 (m, 1H), 1.77–1.46 (m, 2H), 1.03 (t, J =6.8 Hz, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ 83.1, 69.6, 61.0, 38.7, 29.2, 25.9, 19.6. Analytical data was in agreement with that reported in the literature [47] …”

A Cobalt(II) Complex Bearing the Amine(imine)diphosphine PN(H)NP Ligand for Asymmetric Transfer Hydrogenation of Ketones

“…[ 14 ] A moderate ee value of 66 % was obtained on reduction of 1‐acetonaphthone, morehigher than Tomohiko's result, [ 16 ] and the reduced product can be used for the synthesis of (+)‐compactin and 1233A. [ 17 ] A good ee value of 78 % was achieved on hydrogenation of 1‐tetralone, and this value is better than the reported result of Co‐catalyzed borohydride reduction. [ 18 ] Fortunately, when 2‐chlorobenzophenone was used as feedstock, the corresponding alcohol was obtained with 91 % ee value, much more than the result of Co‐catalyzed borohydride reduction, [ 19 ] and the enantiopurity erosion did not happened in this reaction.…”

Synthesis of the (+)-C26–C40 Domain of the Azaspiracids by a Novel Double Intramolecular Hetero-Michael Addition Strategy This work was supported by the United States National Institute of Environmental Health Sciences (NIEHS; grant number ES10615), NIH, and by Bristol-Myers Squibb (CJF). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIEHS, NIH, or BMS. We thank Dr. A. B. Dounay and Dr. G. Florence for critical reading of the manuscript

“…The synthesis of aldehyde 11 began with the known alkyne 12 6 bearing the single C30 stereogenic center (Scheme ). Sequential protection of the alkyne terminus and hydroxyl liberation provided primary alcohol intermediate 13 .…”