Transformation of esters into allyl halides via substituted cyclopropanols. Application in the synthesis of (2S,3R,7R/S)-3,7-dimethyltridec-2-yl acetate and propionate, sex attractants of pine sawfly Diprion pini

Transformation of Esters into 2‐Substituted Allyl Halides via Tertiary Cyclopropanols: Application in the Stereoselective Synthesis of (2S,3S,7S)‐3,7‐Dimethyl‐2‐pentadecyl Acetate, the Sex Pheromone of the Pine Sawfly Neodiprion sertifer

“…The preferential formation of (3 S ,4 S )‐butanolide 2 was observed upon treatment of unsaturated lactone 11 with sodium borohydride in the presence of nickel chloride 7,16. The diastereoselectivity of the reaction was unsatisfactory ( cis ‐ 2 / trans ‐ 2 = 3–4:1) when methanol or ethanol was used as the solvent.…”

“…THP‐protected ethyl ( S )‐lactate ( 8 ) was transformed into bromide 4 by titanium‐catalyzed cyclopropanation of the ethoxycarbonyl group with ethylmagnesium bromide10,11 and subsequent cationic cyclopropyl–allyl isomerization6 of the methanesulfonate of the 1‐substituted cyclopropanol 6 (Scheme ) 7,12. Replacement of the bromine atom in compound 4 with an ethoxycarbonyl group upon treatment with zinc powder, activated by copper(I) chloride in the presence of ethyl chloroformate, resulted in the smooth formation of ester 9 .…”

“…In this work, we report on the stereoselective synthesis of (2 S ,3 S ,7 S )‐3,7‐dimethylpentadecan‐2‐ol ( 1 ) based on the creation of methyl branches in the carbon chain using the transformation of carboxylic esters into 2‐substituted allyl halides via sulfonates of tertiary cyclopropanols 6. Previously, we applied this methodology to the nonstereoselective construction of the methyl‐branched skeleton of 3,7‐dimethyl‐2‐tridecyl acetate and propionate,7 the sex attractants of the pine sawfly Diprion pini ,8 and also to the stereoselective synthesis of the alkaloid (–)‐heliotridane 9…”

Studies towards the Synthesis of (+)‐Lochnerine

“…With compound 18 becoming available, the stage was set for preparing diene 6 . Allyl bromide 19 was prepared readily starting from ( S )‐ethyl lactate by a known 3‐step sequence including the Kulinkovich reaction. N ‐Allylation with allyl bromide 19 cleanly furnished the diene 6 which on treatment with Grubbs’ second generation catalyst yielded the tetracyclic alcohol 20 .…”

New synthesis of syn-stereodiad building block for polyketides. Formal synthesis of arenamides A and C

“…Taking into account broad spectrum of biological activity of arenamides and keen interest of our research team in total and formal syntheses of natural compounds from hydroxy esters [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31], a novel procedure has been developed for the preparation of protected (3S,4S)-3-hydroxy-4-methyldecanoic acid 2 which is the most complex molecular fragment of macrolides 1a-1c (Scheme 1). The starting compound for the synthesis of 2 was (7S)-7-(3-bromoprop-1-en-2-yl)-5,5-dimethyl-4,6-dioxaspiro [2.5]octane (4).…”