3- propylmagnesium bromide

In the present instance, the product is a tertiary alcohol with two methyl groups and one props7 group. Starting from a ketone, the possibilities are addition of methyl-magnesium bromide to 2-pentanone and addition of propylmagnesium bromide to acetone. 

Precomplexation of 2-butylcyclopentanone with methylaluminum bis(2,6-di-hrt-butyI-4-methylphenoxide) (MAD), prior to the addition of methyllithium, leads to the exclusive formation of the equatorial alcohol via cis attack3 4. However, this methodology is apparently not applicable to 3-substituted cyclopentanones. Thus, addition of propylmagnesium bromide to... 

This 1,2-asymmetric induction has been attributed to stcric and stcrcoclectronic factors. Similarly, the cuprate additions to 4-alkylcyclopentenones l7 -19, and 4-alkylcyclohexcnones16 b-18 proceeded with very high trans diastereoselection. The copper iodide catalyzed addition of propylmagnesium bromide to 4-methyl-2-cyclohexenone gave a trans/cis ratio of 80 20, whereas the addition to 5-methyl-2-cyclohexenone produced a transjcis ratio of 93 72 3-Silyloxy system 3 gave the trans-adduct 4 on treatment with butylcopper-boron trifluoride reagent20. 

Thus, Diels-Alder condensation of 9 with methyl vinyl ketone affords the bicyclic adduct 24. The new ring is formed by approach of the dienophile from the face containing the nitrogen bridge, since this is in fact the least hindered side of the molecule (9a). Reaction of the side Chain ketone with propylmagnesium bromide then leads to intermediate 25 demethylation of the... 

It may be mentioned that the optical yield of the analogous reaction between methylneophyltrityltin menthoxide and z-propylmagnesium bromide is different at —15 °C and at 0 °C at —15 °C, optically active (-f)-z-propylmethylneophyltrityl-tin, (+)-(<53), is obtained (see Table 4) whereas at 0 °C optically inactive (63) is obtained 41). 

For the synthesis of Diels-Alder adducts a morphinan-6,8-diene system, as present in thebaine, is indispensable. Older publications started from thebaine and methyl vinyl ketone (but-3-en-2-one), yielding, after a Grignard reaction with propylmagnesium bromide, etorphine (13), a 6,14-endoethenomorphinan that is over 1000x as active as morphine and is used in veterinary medicine (Scheme 5.10). 

Sn2 Reactions with epoxides and aziridines are also synthetically useful. An example of epoxide cleavage with an organocopper reagent with sp carbon moieties is the enantioselective synthesis of (3S, 4S)-4-methyl-3-heptanol (53), an elm bark beetle (Scolytus multistriatus) pheromone [42]. The chiral epoxy oxazolidine 51 [43], prepared from (R)-phenylglycinol, reacted with a propylmagnesium bromide-derived cuprate at —70 °C to afford the oxazolidine 52 in 74% yield (Scheme 9.12). Compound 52 was converted into the target molecular 53 by conventional procedures. 

An interesting method for the introduction of substituents into the 2-position of the quinuclidine ring starting from 3-substituted A2-dehydroquinuclidines (126) has been described.47 By the reaction of methyl J2-dehydroquinuclidine-3-carboxylate (130) with iso-propylmagnesium bromide, 1,4-addition with formation of 2-iso-propyl-3-methoxycarbonylquinuclidine (131) took place instead of a sterically hindered Grignard reaction at the alkoxycarbonyl group. 

Phenylmagnesium bromide gives a 79% yield of product, b.p. 178-180°/11 mm., njf 1.5063 and -propylmagnesium bromide gives 33-42% yields, b.p. 150-153°/22 mm., 1-4429, of alkylation product when essentially the same procedure is used. 

The yield obtained with n-propylmagnesium bromide depends upon the efficiency of separation from the reduction product, ethyl sec-butylcyanoacetate, b.p. 126°/22 mm., nff 1.4277/... 

Nine years later, in 1977,71 Mukaiyama et al. published a full account on the oxidation of magnesium alkoxides with ADD. Thus, magnesium alkoxides were generated by the treatment of alcohols with either -propylmagnesium bromide, or f-butoxymagnesium bromide, and reacted in situ with ADD at room temperature, resulting in good yields of the desired aldehydes or ketones. 

Cognate preparations. 2-Methylpentan-2-ol (tertiary alcohol from a ketone). Use propylmagnesium bromide and acetone. Collect the tertiary alcohol at 121-124°C. 

Addition of a wide range of boronic acids [RB(OH)2] or esters [RB(OR )2] to the pinanediols gives the very stable pinanediol boronic esters. For example, propylboronic acid (available from the addition of propylmagnesium bromide to trimethyl borate followed by acid hydrolysis) and the (s) pinanediol combine to give a homochiral boronic ester as shown in Equation B6.3. 

What compound would be expected as the major product from a Grig-nard reaction between (S)-2,3,3-trimethylbutanal and propylmagnesium bromide ... 

The ester (3) has been shown to be a useful starting point for the synthesis of Elaeocarpus alkaloids. Ester (3) is converted by several steps into the protected keto-aldehyde (4) this, by reaction with n-propylmagnesium bromide followed by a Jones oxidation of the product and then deprotection, gives the diketone (5). As... 

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