The title compound (I) was obtained by EtAlCl₂-promoted asymmetric intramolecular Diels-Alder reaction of the camphorsultam derivative (E,E)-10,10-dimethyl-4-(2,8,10-undecatrienoyl)-3-thia-4-azatricyclo[5.2.1.0^1,5]decane 3,3-dioxide (II); reduction of (I) gave the enantiomerically pure bicyclic alcohol 1,2,4a,5,6,7,8,8a-octahydro-1-naphthylmethanol (III) with regeneration of the unsubstituted chiral sultam precursor (IV) [Oppolzer & Dupuis (1985). Tetrahedron Lett. 26, 44, 5437-5440]. (I): C₂₁H₃₁NO₃S, Mr = 377.6, orthorhombic, P2₁2₁2₁, α = 8.0498 (12), b = 11.973 (2), c = 20.714 (3) Å, V = 1996.4 (5) ų, Z = 4, D_x = 1.256 Mg m^-3, λ(Mo Kα) = 0.71069 Å, μ = 1.735 cm^-1, F(000) = 816, m.p. 477-479 K, [α]²⁰_d = -121.0° (c = 0.51% in CHCl₃) , room temperature, R = 0.052 for 963 observed reflections [lF_ol ≥ 4σ(F_o) and IF_ol ≥ 8.0]. The chirality of enantiomerically pure (I) was confirmed from the known absolute configuration of the camphorsultam moiety as well as by least-squares refinement of the absolute-structure parameter x = 0.05 (31) [Bernardinelli & Flack (1985). Acta Cryst. A41, 500-511].