β‐Cleavage of Bis(homoallylic) Potassium Alkoxides. Preparation of 3‐Hydroxypropyl and 4‐Hydroxybutyl Propenyl Ketones from γ‐ and δ‐Lactones. Synthesis of (±)‐Rose oxide

Abstract

Starting from y-and 6-lactones 1-3, a two-step preparation of 3-hydroxypropyl and 4-hydroxybutyl propenyl ketones 10-18 is described, involving as the key step the B-cleavage of the bis(homoally1ic) potassium alkoxides 4a-9a. This novel methodology is illustrated by a short synthesis of(*)-rose oxide (20).Introduction. -The direct preparation of a y-hydroxy ketone I1 (n = 1) or a 6-hydroxy ketone I1 (n = 2) by the mono-addition of an organometallic reagent RM (M = Li, MgX) to a lactone 1 (n = 1, 2) is generally inefficient due to further rapid addition to the intermediate metaloxy ketone IIa, which leads to diol I11 after protonation of the dialkoxide lIIa (cf. Scheme 1 ) '). We now present an indirect solution to this synthetic problem for allylic organometallic reagents by describing a two-step procedure for the preparation of 3-hydroxypropyl and 4-hydroxybutyl propenyl ketones from y-and 6-lactones, respectively. To illustrate this novel homologation methodology, we also report a synthesis of racemic rose oxide (20)2), a naturally occurring compound [3] which has incited much synthetic work because of its extensive use in perfumery [4].

Structure Elucidation, Enantioselective Analysis, and Biogenesis of Nerol Oxide in Pelargonium Species

“…Compounds 10 and 11 were prepared by partial reduction of 9a in a micromole scale according to Ohloff et al (1964). MS data are in agreement with the data given by Snowden et al (1987).…”

Biogenesis of Geranium Oil Compounds: On the Origin of Oxygen in cis-/trans-Rose Oxide

“…The diastereomeric ratio of cis-and trans-rose oxides which are generated by cyclization of 18/19 is 3/1 (Patel et al, 1977;Snowden et al, 1987) and is identical with the genuine cis/trans ratio in Pelargonium plants. The labeled rose oxides 9-12 resulting from the fed precursor 15 also show a cis/trans ratio of 3/1 (see Table 1).…”

A convenient preparative method of oxo‐dimethylallyl compounds from carboxylic acid derivatives

“…A variety of methods of synthesizing ketones using allylic Grignard reagents have been reported.' '- 15 Our technique is a convenient and useful one for the preparation of 0x0-dimethylallyl compounds from carboxylic acid derivatives using allylic Grignard reagents via two steps. Using this method, tetrahydroegomaketone could be obtained.…”