Heterocyclic Chiral Auxiliaries in Total Synthesis of Natural Products

Heterocyclic chiral auxiliary is widely considered to be an efficient choice to bring about asymmetric induction in the stereoselective synthesis of natural products. Various heterocyclic chiral auxiliaries are frequently used in asymmetric alkylation, Di

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Heterocyclic Chiral Auxiliaries in Total Synthesis of Natural Products Akriti Srivastava, Kirana D. Veeranna, and Sundarababu Baskaran

Abstract Heterocyclic chiral auxiliary is widely considered to be an efficient choice to bring about asymmetric induction in the stereoselective synthesis of natural products. Various heterocyclic chiral auxiliaries are frequently used in asymmetric alkylation, Diels-Alder, Michael addition, and aldol reaction to synthesize complex chiral intermediates in enantiomerically pure form that are further employed in the synthesis of natural targets of biological and pharmaceutical importance. Amongst the various auxiliaries, Evans’ oxazolidinones and their sulfur analogues are the most sought after chiral auxiliaries in asymmetric synthesis owing to their ability to induce good to excellent selectivities. The versatility of oxazolidinones is brought forth by their utilization in the total synthesis of complex natural targets like brefeldin A, calcaripeptides A, B, and C, and apoptolidinone. In addition to Evans’ oxazolidinones, this chapter will also focus on application of Enders’ SAMP/RAMP hydrazone, camphorsultam, phosphonamide, pyrimidinone, and oxazolinyl ketone as chiral auxiliaries in the total synthesis of natural products and bioactive molecules. Keywords Asymmetric synthesis · Camphorsultam · Enantioselective total synthesis · Heterocyclic chiral auxiliaries · Imidazolidinone · Natural products · Oxazolidinone · Oxazolinyl ketone · Phosphonamide · Pyrimidinone · SAMP/ RAMP hydrazine Contents 1 Introduction 2 Oxazolidinone-Based Chiral Auxiliaries 2.1 (+)-Brefeldin A 2.2 Baulamycin A

A. Srivastava, K. D. Veeranna, and S. Baskaran (*) Department of Chemistry, Indian Institute of Technology Madras, Chennai, India e-mail: [email protected]; [email protected]; [email protected]

A. Srivastava et al. 2.3 Calcaripeptides A–C 2.4 Glucolipsin A 2.5 Apoptolidinone 2.6 Bleomycin A 2.7 Brasilinolide A 2.8 FD-891 2.9 ()-FR182877 3 Pyrrolidine-Based Chiral Auxiliaries 3.1 (+)-Streptenol A 3.2 ()-α-Elemene 3.3 ()-Neonepetalactone, Dehydroiridodial, and Dehydroiridodiol 3.4 (+)-Sordidin 3.5 ()-Callystatin A 4 Sulfur-Based Chiral Auxiliaries 4.1 ()-Manzacidin B 4.2 (+)-Bakuchiol 5 Phosphorous-Based Chiral Auxiliaries 5.1 Methyl Jasmonate 5.2 ()-Anthoplalone 5.3 ()-Berkelic Acid 5.4 (+)-Ambruticin S 5.5 Estrone 5.6 Nudiflosides A and D 6 Imidazolidinone-Based Chiral Auxiliaries 6.1 ()-Lavandulol 7 Pyrimidinone-Based Chiral Auxiliaries 7.1 Oxyneolignan 8 Oxazolinyl Ketone as Chiral Auxiliaries 8.1 ()-Rhazinilam References

1 Introduction Most biologically active molecules as well as pharmaceutical targets exist as a single enantiomer; henceforth, chemical syntheses of such natural products and pharmaceutically active molecules are designed to obtain the natural products in enantiomerically pure form [1]. The development of asymmetric synthesis is one of the most challenging aspects in organic synthesis, and various protocols have been demonstrated by the chemists worldwide to