𝔖 Bobbio Scriptorium
✦   LIBER   ✦

A cyclobutene bridgehead olefin approach to the germacranes

✍ Scribed by Stuart L. Schreiber; Conrad Santini

Publisher
Elsevier Science
Year
1981
Tongue
French
Weight
185 KB
Volume
22
Category
Article
ISSN
0040-4039

No coin nor oath required. For personal study only.

✦ Synopsis

Sumnary: A model study for the synthesis of the germacranes is described which utilizes a consecutive oxy-Copelcyclobutene ring opening rearrangement sequence. The e,y-unsaturated enone necessary for the rearrangement is obtained directly from the photocycloaddition of ailene and cyclohexenone. We are interested in developing a strategy for the synthesis of germacranes that involves the construction of a ten-membered carbocyclic ring containing the butadiene unit as in 1. This type of structural unit is found to occur in such members of the germacrane class as germacrene Dt 2, and periplanone-B 2,3 , 3. It could also serve as a useful precursor to the functionality found at these carbon centers in the other members 4 of this structural class. Our approach to the cyclic diene involves the use of a consecutive oxy-Cope/cyclobutene ring opening rearrangement sequence and utilizes the regioselectivity observed in the photocycloaddition of allene to cyclohexenones. Photocycloaddition ofsallene to cyclohexenone regioselectively generated the B,y-enone 4, as reported previously. Addition of vinyl magnesium bromide (THF, -70') to 4 gave a 79% yield of the tertiary alcohol, 5. The assignment of the endo alcohol stereochemistry

πŸ“œ SIMILAR VOLUMES

Ready access to bridgehead olefinic isom
Ready access to bridgehead olefinic isomers of the triquinacene skeleton
✍ Holger ButenschΓΆn; Armin de Meijere πŸ“‚ Article πŸ“… 1983 πŸ› Elsevier Science 🌐 French βš– 264 KB

l-Halo-and 1,4-dihalotriquinacenes readily react with secondary amines and alkyl lithium compounds to yield bridgehead olefinic and double bridgehead olefinic derivatives of the tricyclo[5.2.1.04\*10 ldecatriene system, probably by an $2' type attack of the soft nucleophile. The long searched-for ac

Electrophilic Additions to Strained Brid
Electrophilic Additions to Strained Bridgehead Olefins. Estimation of Strain by Comparison with the Solvolysis of Bridgehead Bromides
✍ Konrad B. Becker πŸ“‚ Article πŸ“… 1977 πŸ› John Wiley and Sons 🌐 German βš– 507 KB

## Abstract The addition of water, acetic acid, and hydrogen bromide to the strained bridge‐head olefins bicyclo[3.3.1]‐1(2)‐nonene **(1)**, bicyclo[4.2.1]‐1(8)‐nonene **(2)**, and bicyclo[4.2.1]‐1(2)‐nonene **(3)** gives exclusively the bridgehead alcohols, acetates, and bromides, respectively. Th

New applications of the wittig reaction
New applications of the wittig reaction to the preparation of strained bridgehead olefins
✍ William G. Dauben; Jeffrey D. Robbins πŸ“‚ Article πŸ“… 1975 πŸ› Elsevier Science 🌐 French βš– 204 KB

In the past few years there has been a rapid growth of interest in the n preparation of strained bridgehead olefins'. Until recently the reported synthetic approaches all involved a separate construction of the ring system prior to introduction of the double bond. In 1973, however, a facile synthesi

A ring-closing olefin metathesis approac
A ring-closing olefin metathesis approach to bridged azabicyclic structures
✍ Christopher E Neipp; Stephen F Martin πŸ“‚ Article πŸ“… 2002 πŸ› Elsevier Science 🌐 French βš– 136 KB

A facile and general entry to functionalized bridged bicyclic nitrogen heterocycles has been developed that involves the ring-closing metathesis (RCM) of cis-2,6-dialkenyl-N-acyl piperidines that were readily prepared from glutarimide or 4methoxypyridine.