312. Further investigations in the butenyl–boron trichloride system

Abstract

Gerrard, La##ert, and Silver. 1647* The composition (i.e., relative percentages of Iand 3-methylallyl compounds) of the product is shown in Table 2 and similarly for subsequent reactions involving 1-and 3-methylallyl derivatives.

Reactions Of Boron Trichloride With Organic Compounds

“…] and ¿erf-butyl (61, 64) dichloroboronites could not be obtained, although analytical evidence [R = f-C3H7 (64), s-C4H9 (61)] and isolation of a pyridine complex [R = n-CeHi3(CH3)CH (64)] at -80°C. demonstrated the existence of some of these at low temperatures; similar evidence could not be obtained for the ¿erf-butyl (61), 1-and 3-methylallyl (74), benzyl (7), or carbethoxymethyl (52) dichloroboronites. The failure to obtain carbalkoxy-substituted alkyl dichloroboronites was attributed to the competing ester-fission reaction (see Section XI) (52).…”

“…in an inert solvent such as n-pentane. It has been demonstrated with a selection of primary [R = n-C3H7 (64); n-C4H9, f-C4H9 (61); n-C5Hu (2); ¿-C4H9CH2, n-C8H17 (64); = 2, CH2=C(CH3)CH2 (71); CH3CH=CHCH2, CH2=CHCH2CH2 (74); CH=CCH2 (71); C1(CH2)2 (46); C1(CH2)3 (2); C1(CH2)« (46); C1(CH2)5, CH2C1CHC1CH2 (2); CC13 (22); CF,CH2 (4); C2H6OOCCH2, C2H6OOC(CH2)2 (52)] and also secondary alcohols [R = s-C4H9 (61); f-C3H7(CH3)CH, ¿-C4H9(CH3)CH (64); n-C6H13(CH3)CH (60); CH2=CH(CH3)CH ( 74 Exceptions were those alcohols [R = C6H5CH2 (7), CeHs(CH3)CH (60)] which have a propensity for preionization, when the major product was the alkyl chloride (equation 3), this being the exclusive stoichiometry for an unsubstituted tertiary alcohol (R = ¿-C4H9 ( 61)). Boron trichloride may, however, be used for the preparation of tert-alkyl (as well as less highly branched) borates, by adding the trichloride (1 mole) to a mixture of the alcohol and pyridine (3 moles of each) in an inert solvent such as n-pentane, chloroform, or methylene dichloride at low temperature ( -10°to -80°C.…”

“…Chloroboronates were not obtained as compounds stable at 20°C. if the alkyl group was powerfully electron-releasing [R = CH2=CHCH2, CH2=C(CH3)CH2 ( 71); CH3CH=CHCH2, CH2=CH-(CH3)CH (74); C6HsCH2 (7), C6H6(CH3)CH ( 60), ¿-C4Ii9 (61, 101)], although in some of these cases [R = CH2=CHCH2, CH2=C(CH3)CH2 ( 71); CH^CH-(CHa)CH (74)] it was possible to isolate their stable pyridine (1:1 or 1:2 py) complexes by addition of pyridine to the freshly prepared reaction mixture 7…”

“…(v) The complex between di-2-chloroethyl ether and boron trichloride dissociated into its components as well as decomposing according to equation 33 (48). (vi) Phenyl allyl ether underwent an ortho-Claisen rearrangement (equation 35) (73).…”

The Zinc Chloride Catalyzed Migration of Halogen in the Claisen Rearrangement

“…For example, treat~nent of the allyl ether of guaiacol with BF?.2CH,COzH a t 68" gave 38% of eugenol as well as some guaiacol, 6-allylguaiacol, and the allyl ether of allylguaiacol or eugenol (12). Also, allyl phenyl ether a t -80' was converted by boron tricliloride exclusively to o-allylphenol (13). Furthermore, a recent study (14) showed that boron trichloride effected the intramolecular rearrangement in high yields (90-98%) of allyl phenyl ether to 2-allylphenol, ally1 P-tolyl ether to 2-allyl-4-methylphenol, allyl 2,6-dimethylphenyl ether t o a mixture of 2,G-dimethyl-3-allylphenol and 2,G-dimethyl-4-allylphenol, and also allyl nlesityl ether t o S-allylmesitol.…”