Organometallic and radical cyclizations involving allenes and acetylenes

Thesis/Dissertation · Tue Dec 31 23:00:00 EST 1991

OSTI ID:5720038

Ayers, T A

The present work expands the knowledge of the reactivity of the allene in organometallic and radical cyclizations. A systematic investigation of the cyclizations of [omega]-allenyl organometallic reagents R[sub 1]R[sub 2]C[double bond]C[double bond]CR[sub 3](CH[sub 2])[sub n]CH[sub 2]M (M = Li, CuCNLi) demonstrated that the allene is an excellent site for intramolecular organometallic additions. The effects of substitution at the allene and the disposition of the allene and organometallic center were varied to establish the scope of cyclization. Cyclization of lithium derivatives with n=1 and n=2 occurred in favorable cases at the central allenyl carbon to provide good yields of cyclobutanes and cyclopentanes. Competing processes occurred for the n=3 systems with M = Li, but the corresponding cuprate (M = CuCNLi) cyclized efficiently at the proximate allenyl carbon to generate vinylcyclopentane systems. Little cyclization was observed with n=4 (M = Li, CuCNLi). In these reactions both the acyclic and cyclic organometallic species were reacted with several electrophiles demonstrating the synthetic potential of this methodology. Substitution of radical stabilizing groups on [omega]-allenyl radicals CH[sub 2][double bond]C[double bond]CZ(CH[sub 2])[sub n]CH[sub 2][center dot], where Z = P(O)Ph[sub 2], S(O)Ph, and SO[sub 2]Ph, increased the efficiency and regiochemistry of radical cyclization compared with simple [omega]-allenyl radicals. The ability of these functionalized [omega]-allenyl radicals to generate six- and even seven-membered carbocycles in good yield is demonstrated. Radical attack occurred exclusively at the central allenyl carbon for n = 2--5, whereas addition to the proximate allenyl carbon was observed for n=1. Also included is an investigation of the reactivity of R[sub 1]C[triple bond]C(CH[sub 2])[sub 3]CHIR[sub 2], with metallic zinc. In these reactions, a substantial amount of (1-iodoalkylidene)cyclopentanes were generated by radical intermediates.

• Research Organization: Indiana Univ., Bloomington, IN (United States)
• OSTI ID: 5720038
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ACETYLENE
ACTIVATION ENERGY
ALKALI METALS
ALKYNES
ALLENE
CHEMICAL REACTIONS
COPPER
CYCLIZATION
DIENES
ELEMENTS
ENERGY
HYDROCARBONS
LITHIUM
METALS
ORGANIC COMPOUNDS
ORGANOMETALLIC COMPOUNDS
POLYENES
RADICALS
TRANSITION ELEMENTS