Enantioselective Synthesis and X‐ray Structure of (+)((4aS,5S,8aS)‐5,8a‐Dimethyl‐7‐methyleneoctahydro‐2H‐spiro[naphthalene‐1,2′‐[1,3]dioxolan]‐5‐yl)methyl‐4‐iodobenzoate

• Published in: European journal of organic chemistry 2019-02, Vol.2019 (7), p.1594-1599
• Main Authors: Leonelli, Francesca, Trombetta, Andrea, La Bella, Angela, Lucarelli, Giulio, Demitri, Nicola, Lamba, Doriano, Migneco, Luisa Maria, Marini Bettolo, Rinaldo
• Format: Article
• Language: English
• Subjects: Aldehydes; Aldol reactions; Amino acids; Asymmetric synthesis; Cyclization; Dehydration; Enantiomers; Enantioselectivity; Naphthalene; Stereochemistry; X-ray diffraction
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.201801771

The d and l amino acid mediated enantioselective intramolecular aldol reaction of 4‐((1‐methyl‐2,6‐dioxo‐cyclohexyl)methyl)‐pent‐4‐enal 1 leading, after dehydration, to (‐)‐(R) and (+)‐(S) 4a‐methyl‐3‐methylene‐5‐oxo‐2,3,4,4a,5,6,7,8‐octahydro‐naphthalene‐1‐carbaldehyde 2 was explored. It was found that (‐)‐(R) carbaldehyde 2 is enantioselectively formed in the presence of l‐amino acids while (+)‐(S) carbaldehyde 2 is enantioselectively formed in the presence of d‐amino acids. (‐)‐(R) Carbaldehyde 2 was then transformed into (+)‐22. The absolute configuration and relative stereochemistry of the latter was established by single‐crystal X‐ray diffraction analysis of p‐iodobenzoate (+)‐23. The d and l amino acid mediated enantioselective intramolecular aldol reaction of 1 leading, after dehydration, to (‐)‐(R) and (+)‐(S) 2 was explored. It was found that (‐)‐(R) carbaldehyde 2 is enantioselectively formed in the presence of l‐amino acids while (+)‐(S) carbaldehyde 2 is enantioselectively formed in the presence of d‐amino acids.