title: Highly regioselective Diels-Alder reactions toward oroidin alkaloids: use of a tosylvinyl moiety as a nitrogen masking group with adjustable electronics.
abstract: [reaction: see text] The use of the p-toluenesulfonyl (Ts) and tosylvinyl (Tsv) groups as nitrogen masking groups imparted high regioselectivity in Diels-Alder reactions directed toward members of the oroidin-derived marine alkaloid family. The electron-withdrawing Tsv group was utilized as an electronically adjustable nitrogen-protecting group as subsequent hydrogenation provided the more electron-rich tosylethyl (Tse) group. This electronic adjustment strategy avoided a protecting group exchange and provided the required electronics for the key chlorination/ring-contraction sequence.
authors.affiliation: Department of Chemistry, Texas A and M University, P.O. Box 30012, College Station, Texas 77843-3012, USA.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Dransfield
authors.forename: Shaohui
authors.initials: S
authors.lastname: Wang
authors.forename: Anja
authors.initials: A
authors.lastname: Dilley
authors.forename: Daniel
authors.initials: D
authors.lastname: Romo
mesh_terms: D000470:Alkaloids / Q000737:chemistry*; D000588:Amines / Q000138:chemical synthesis; D015394:Molecular Structure; D011758:Pyrroles / Q000737:chemistry*; D013141:Spiro Compounds / Q000737:chemistry; D013237:Stereoisomerism; D014105:Tosyl Compounds / Q000737:chemistry; D014753:Vinyl Compounds / Q000737:chemistry
chemical_list: D000470:Alkaloids; D000588:Amines; D011758:Pyrroles; D013141:Spiro Compounds; D014105:Tosyl Compounds; D014753:Vinyl Compounds; C077209:oroidin