Stereospecific introduction of functionalized angular methyl groups via the Claisen rearrangement. Octalin and hydrindenyl ring systems

Abstract

The one-step Claisen rearrangement using ethyl vinyl ether, N,N-dimethylacetamide dimethyl acetal, or t,riethyl orthoacetate provides a useful method for the preparation of octalin systems with functionalized angular methyl groups from octalols.However, preparation and purification of vinyl ethers followed by thermolysis lead to functionalized methyl groups in both ring systems. The use of decalin as solvent in the thermolysis increases the amount of Claisen product in the hydrindeny1 system. When the temperature is lowered, the rate of rearrangement is decreased and the amount of elimination increased.This method fails with the hydrindenyl ring system.

1,3‐Chirality Transfer by Fragmentation of Allylsulfinic Acids: A Diastereoselective Approach to Vinyl Bromides Related to trans‐Hydrindane or trans‐Decalin

“…1 H NMR (200 MHz): δ = 0.99 (s, 3 H, CH 3 ), 1.14 (s, 9 H,C(CH 3 ) 3 ), 1.19–2.16 (m, 9 H), 2.34–2.56 (m, 1 H), 3.37 (t, J = 8.2 Hz, 1 H, 1‐H), 4.16–4.34 (br., 1 H, 5‐H), 5.28–5.36 (m, 1 H, 4‐H) ppm. 13 C NMR (50 MHz): δ = 17.3 (CH 3 ), 26.0, 28.8(C( C H 3 ) 3 ), 29.7, 29.8, 34.2, 43.3 (C‐7a), 68.8 (C‐5), 72.6( C (CH 3 ) 3 ), 80.2 (C‐1), 122.2 (C‐4), 149.4 (C‐3a) ppm, in agreement with data reported elsewhere 28…”

Catalyzed Reactions of Enol Ethers with SN1 Active Groups: A Novel Method for the Preparation of α‐Alkylated Ketones

“…General Procedure B ± Mercury-Catalyzed Vinylation of Allylic Alcohols [19] : Mercury(II) acetate (0.2 equiv) was dried prior to the reaction by gentle heating under vacuum and dissolved under an argon atmosphere in freshly distilled ethyl vinyl ether. To this solution the allylic alcohol (1 equiv) was added and the mixture was stirred for 5 days at ambient temperature.…”

Introduction of Bicyclic Ketal Chemistry: Synthesis and Transformation Reaction of 6,8-Dioxabicyclo[3.2.1]octane Skeletal System

“…[3,3]-Sigmatropic shift, especially the Claisen rearrangement, has been utilized for introduction of allyl groups on benzene rings. 51 This reaction is known to proceed stereoselectively by a concerted mechanism via a chair cyclohexane transition state 52 and the equlibrium in this reaction depends upon the relative stability of product and starting material. Buchi has taken advantage of this [3,3]sigmatropic shift to gain entry into the substituted cyclohexene system.…”