SYNTHESES IN THE TERPENE SERIES: VIII. SYNTHESIS OF THE CIS- AND TRANS-ISOMERS OF 7,7,10-TRIMETHYLDECAL-1-ONE. A CONVENIENT MODIFICATION OF THE BROWN HYDRATION REACTION

Abstract

7,7,10-~rimeth~l-~~(~)-octal-2-one (VII) was converted to the cycloethylenedithiolcetal (VIII), which on Raney nickel reduction yielded 7,7,10-trimethyl-~1(g)-octalin (IX). Oxidation with perbenzoic acid led to the corresponding oxide (X), which could be rearranged in low yield to an equilibrium mixture of 7,7,10-trimethyldecal-1-one consisting essentially of the trans-isomer (XI).A convenient modification of the Brown hydration reaction is described, whereby the necessity of generating diborane or of using diglyme is avoided. 7,7,10-~rimetl~~l-~~(~)-octalin (IX) on Brown hydration using this modification stereospecifically furnished 7,7,10/3-trimethyl-cis-decal-1/3-01 (XII), which was oxidized to 7,7,10-trimethyl-cis-decal-1-one (XIII). Isomerization resulted in the above-described equilibrium mixture containing a t least 90% of the trans-isomer (XI). Similarly, the previously described 10-methyl-~l(g)-octalin (XVI) yielded a mixture of the cis-and trans-isomers of 10-methyldecal-1-one (XIX). Syntheses of 2-rnethylene-7,7,10-trimethyl-~1(g)-octalin (XIV) and of 7,7,10-trimethyl-cis-decal-2,3-dione 3-dithiotrimethylene ketal (XXII) are also described.In Part V of this series (1) stereospecific syntheses of the bicyclic ketones (Ia) and (Ib) were described, compounds which could become rings A and B of triterpenes of the P-amyrin (111) type. For the construction of rings D and E, ketones of type (11) are required which are to be joined to the ketones (I) by a two-carbon unit, probably best introduced as acetylene. In this connection a study of the synthesis and stability of 10-methyldecal-1-one has already been carried out (2).The substances of particular interest are the ketones (IIa) and (IIb) of the cis-configuration. Conformational considerations show that the derived acetylenic carbinols on dehydration should give vinyl-acetylenes with the double bond a t the required A1(2)-position, whereas the corresponding trans-ketones would be expected to give vinylacetylenes with the double bond a t the less desirable

Advanced Organic Chemistry

“…This procedure has the opposite regioselectivity to the direct ionic addition of hydrogen bromide to terminal alkenes. 58 CHiCH2)6CH=CH2 ~~ !~7~,CCH-,), ~ CHiCH2)sBr (69 %) 3) Br, 56. R. C. Lamb, P. W. Ayers, M. K. Toney, and J. F. Garst, 1.…”

Theoretical study on the reaction mechanism of “ligandless” Ni-catalyzed hydrodesulfurization of aryl sulfide

“…Moreover, the cleavage of C-S bonds in organosulfur compounds makes extensive use of removal of blocking groups 6 and temporary directing groups. 7 Hydrodesulfurization, i.e., cleaving the C-S bond to form C-H bond, plays an importance role in manufacturing nonpolluting fuel from natural resources.…”

Preparation and reactions of .beta.-chloro-.alpha.,.beta.-unsaturated ketones

“…Acetylacetone (29, 5.0 g, 50 mmol) in chloroform (15 ml) was treated with oxalyl chloride (12.7 g, 100 mmol) and the resulting solution was refluxed for 15 min. Gas chromatography (column B, 150') showed one component at retention time 4.0 min: ir (film) 5.92,6.23,6.40,6.90, 7.75 p; NMR (CCW 6 (Z)-2-Chloromethylene-4a-methyl-4,4a,5,6,7,8-hexahydronaphthalen-2(3H)-one (35). bp 42' (11 mm)].…”

“…Finally, the amount of silver used in preparing the couple is important. The couple is prepared by adding the acid-washed zinc dust to a hot solution of silver acetate in acetic acid, and the most effective reagent is obtained when [30][31][32][33][34][35][36][37][38][39][40] a Yields are distilled yields, b These reactions were carried out in benzene; all others were carried out in chloroform.…”

“…Chloroethylidinecyclohexanone (27). Oxalyl chloride (66.0 g, 460 mmol) waa added slowly to methyl dimedone (16,3435.0 g, 227 mmol) in benzene (40 ml) and the resulting solution was refluxed for 3 hr. Oxalyl chloride (66.0 g, 460 mmol) waa added slowly to methyl dimedone (16,3435.0 g, 227 mmol) in benzene (40 ml) and the resulting solution was refluxed for 3 hr.…”