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Introduction of angular methyl groups

The transformation of 14 into 7-methoxy-fra 5-3a,9b-dimethyl-l,3,3a,4,5,9b-hexahydro-2/f-benz[e]inden-2-one (15) illustrates the use of the sequence consisting of cyclopropanation, followed by dissolving metal reduction, for the introduction of angular methyl groups into structures containing condensed alicyclic rings. [Pg.2491]

A soln. of crude 2-(a-bromobenzyl)-2-norbornanol in anhydrous benzene treated at 0° with 1 equivalent isopropylmagnesium bromide, and refluxed 0.5 hr. 3-phenylbicyclo[3.2.1]octan-2-one. Y 64%. A. J. Sisti, Tetrah. Let. 1967, 5327 stereospecific introduction of angular methyl groups via this reaction s. Tetrah. Let. 1969, 2269. [Pg.219]

Addition C C CHCR Introduction of angular methyl groups... [Pg.498]

The key reaction in these syntheses was the stereoselective introduction of angular cyano groups as latent methyl groups into perhydropolycyclic a, (3-unsaturated compounds. The new hydrocyanation method developed gave excellent chemoselectivity and stereochemical control. [Pg.145]

An example is the preparation of 18-trideuterio 5a-steroids bearing a side chain at C-17. Labeling of this position with three deuteriums was accomplished by utilizing the Johnson procedure for steroid total synthesis. This synthesis involves, in part, introduction of the 18-angular methyl group by methylation of the D-homo-17a-keto-17-furfurylidene intermediate (243). By substituting d3-methyl iodide in this step, the C/D cis- and ra/J5-18,18,18-d3 labeled ketones [(244) and (245)] are obtained. Conversion of the C/D tra 5-methylation product (245) into 18,18,18-d3-d /-3)8-hydroxy-5a-androstan-17-one (246) provides an intermediate which can be converted into a wide variety of C-18 labeled compounds of high (98%) isotopic... [Pg.208]

Ethers have been prepared by the thermal lead tetraaeetate method in 60-71% ° yield. Introduction of an axial 3a-acetoxy function into 5a-H steroids, however, seems to change the conformation of ring A in such a way that the distance of the 2/ -oxygen from the angular methyl group is considerably increased. Consequently the 2/5,19-ether is formed in only 0.7% to 24% yield. " 02... [Pg.244]

Introduction of functionalized angular methyl groups.2 The reaction of ethyl vinyl ether with 10-methyl-A1 <9 -2-octalol (1) catalyzed by mercuric acetate in a sealed Carius tube for 12 hr. at 200° gives 9-formylmethyl-10-methyl-A1-octalin (2, 85% yield) together with some dienes (3,15 % yield). Use of phosphoric acid leads only to the dienes (3). The one-step procedure involves formation of the vinyl ether followed by Claisen... [Pg.455]

Introduction of the cyclopropane moiety with the correct stereochemistry in the cyclopen tenone subunit was successful in creating an angular methyl group at the C/D junction of the trans-hydrindane ring system of paspalicine, an indole diterpene mould metabolite. ... [Pg.266]


See other pages where Introduction of angular methyl groups is mentioned: [Pg.190]    [Pg.475]    [Pg.941]    [Pg.308]    [Pg.437]    [Pg.324]    [Pg.219]    [Pg.37]    [Pg.427]    [Pg.28]    [Pg.581]    [Pg.170]    [Pg.190]    [Pg.475]    [Pg.941]    [Pg.308]    [Pg.437]    [Pg.324]    [Pg.219]    [Pg.37]    [Pg.427]    [Pg.28]    [Pg.581]    [Pg.170]    [Pg.358]    [Pg.296]    [Pg.82]    [Pg.242]    [Pg.159]    [Pg.245]    [Pg.178]    [Pg.113]    [Pg.129]    [Pg.82]    [Pg.73]    [Pg.302]    [Pg.147]    [Pg.66]    [Pg.66]    [Pg.203]    [Pg.23]    [Pg.717]    [Pg.502]    [Pg.57]    [Pg.31]    [Pg.709]    [Pg.18]    [Pg.858]    [Pg.48]    [Pg.219]    [Pg.339]   


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