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34.1.6.4.3 Substitution of Other Groups

DOI: 10.1055/sos-SD-134-00125

Yamazaki, T.Science of Synthesis Knowledge Updates, (20172290.

3-Fluoroallyl phosphate 26 is an excellent substrate for SN2′-type reactions for its conversion into 3-substituted 3-fluoroprop-1-enes.[‌21‌] As shown in Scheme 12, substrate 26 usually prefers to undergo nucleophilic attack at the position γ to the leaving phosphonyloxy group, usually in a regiospecific manner, whereas it undergoes attack at the α-position in the presence of sterically demanding nucleophiles bearing isopropyl or tert-butyl groups (R1M = iPrMgBr and t-BuMgBr). The same γ-regioselectivity is also observed if the ethoxycarbonyl group in substrate 26 is replaced by a phenyl moiety, which furnishes products corresponding to 27 and 28 in quantitative yield (as determined by 19F NMR spectroscopy) in a ratio of 97:3. Noteworthy, however, is the fact that reduction of the amount of copper(I) cyanide to 0.2 equivalents without altering any other conditions causes a drastic change in the regioselectivity, with a ratio (27/28) of 19:81. The analogue of 26 bearing a phenyl group in place of the ethoxycarbonyl group behaves in a similar manner if butyllithium is used as R1M.[‌22‌]

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M8 M Meee (°M) Meeee (88/88) Meeeee (%) Mee
Me MeMe −88 888:8 (88) [‌88‌]
Me MeMe −88 888:8 88 (88) [‌88‌]
Me MeMe −88 888:8 88e (88) [‌88‌]
eMe MeMe −88 88:8 88 (88) [‌88‌]
e-Me MeMe −88 8:888 88 (88) [‌88‌]
Me Me −88 888:8 (88) [‌88‌]
Me Me −88 888:8 88 (88) [‌88‌]
Me MeMe 8 888:8 88e (88) [‌88‌]
eMe Me(eMe) 8 888:8 88e (88) [‌88‌]

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Meeeee 88 Meeeeeeee ee 8-Meeeeeeeeee (M)-8-(Meeeeeeeeee)eeeee-8-eeee[‌88‌]

Meeeeeeeeee 88

M8 M8 M8 eee (%) Meeee (%) Mee
Me M Me 88 88 [‌88‌]
Me M 8-MeM8M8 88 88 [‌88‌]
Me M 8-MeMM8M8 88 88 [‌88‌]
Me M Me 88 88 [‌88‌]
8-MeM8M8 M Me 88 88 [‌88‌]
8-Mee M Me 88 88 [‌88‌]
Me Me M 88 88 [‌88‌]
(MM8)8M8 M M 88 88 [‌88‌]

e Meeeeeeeee ee MMMM.

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Meeeeeeeeee 88

M8 M8 M8 e ee ee (%) Meeee (%) Mee
M M Me 8 88:8 88 88 [‌88‌]
M M 8-MeM8M8 8 88:88 88 88 [‌88‌]
M M 8-MeM8M8 8 88:8 88 88 [‌88‌]
M M 8-MeM8M8 8 88:8 88 88 [‌88‌]
M M 8-MeMM8M8 8 88:8 88 88 [‌88‌]
M M 8-MeM8MM8M8 8 88:88 88 88 [‌88‌]
M M MM=MMe8 8 88:8 88 88 [‌88‌]
M M Me 8 88:88 88 88 [‌88‌]
M M Me 8 88:88 88 88 [‌88‌]
M M Me 8 88:8 88 88 [‌88‌]
Me M Me 8 88:88 88 88 [‌88‌]
M MMe Me 8 88:88 88 88 [‌88‌]

Meeeeeeeeeee Meeeeeeee

Meeee 8-Meeeeeeee-8-eeeeeee 88; Meeeeee Meeeeeeee:[‌88‌]

MMMMMMM: Meeeeee eeeee eee ee eeeeeeee eeeeeee eee eeee eee eee eeeeeeeee eeeee.

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Meeee Meeeeeee 88; Meeeeee Meeeeeeee eee Meeeeeeeeeeeeeeeeeeeee Meeeeeeee eeee Meeeeeeee:[‌88‌]

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References


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