title: Crystal structures of 3,6-di-allyl-tetra-cyclo[6.3.0.0(4,11).0(5,9)]undeca-2,7-dione and 1,7-di-allyl-penta-cyclo-[5.4.0.0(2,6). 0(3,10).0(5,9)]undecane-8,11-dione: allyl-ated caged compounds.
abstract: The title compounds, C17H20O2 (1) and C17H18O2 (2), are allyl-ated caged compounds. In (1), the carbon atoms bearing the allyl groups are far apart [2.9417 (17) Å], hence the expected ring-closing metathesis (RCM) protocol failed to give a ring-closing product. When these carbon atoms are connected by a C-C bond as in (2), the distance between them is much smaller [1.611 (3) Å] and consequently the RCM process was successful. The caged carbon skeleton of (1) can be described as a fusion of four five-membered rings and one six-membered ring. All four five-membered rings exhibit envelope conformations. The structure of compound (2) consists of four five-membered rings, of which two are cyclo-penta-none rings bonded at the 2, 4 and 5 positions and linked at the 3-carbons by a methyl-ene bridge. It also consists of one four-membered and two six-membered rings. All four five-membered rings adopt envelope conformations. In the crystal of (1), mol-ecules are linked via C-H⋯O hydrogen bonds, forming sheets lying parallel to (010). In the crystal of (2), mol-ecules are linked via C-H⋯O hydrogen bonds forming chains along [100].
authors.affiliation: Department of Chemistry, Indian Institute of Technology-Bombay, Powai, Mumbai 400 076, India.
authors.forename: Sambasivarao
authors.initials: S
authors.lastname: Kotha
authors.affiliation: Department of Chemistry, Indian Institute of Technology-Bombay, Powai, Mumbai 400 076, India.
authors.forename: Vital
authors.initials: V
authors.lastname: Seema
authors.affiliation: Department of Chemistry, Indian Institute of Technology-Bombay, Powai, Mumbai 400 076, India.
authors.forename: Deepak
authors.initials: D
authors.lastname: Deodhar
authors.affiliation: Department of Chemistry, Indian Institute of Technology-Bombay, Powai, Mumbai 400 076, India.
authors.forename: Mobin
authors.initials: M
authors.lastname: Shaikh
keywords: Crystal structure; Diels–Alder reaction; [2 + 2] cyclo­additions; caged compounds; crystal structure; penta­cyclo [5.4.0.02,6.03,10.05,9]undecane (PCUD); ring-closing metathesis (RCM)