0 Hits

  • Previous / Next

You are using Science Of Synthesis as a Guest.
Please login or sign up for a free trial to access the full content. Variation 4: Using Other Alkenyl Anions

DOI: 10.1055/sos-SD-005-00498

Crisp, G. T.Science of Synthesis, (20035524.

The hydroalumination of substituted prop-2-yn-1-ols, followed by the addition of electrophilic trialkylstannanes, provides ready access to a variety of functionalized Z-alkenylstannanes. For example, addition of lithium aluminum hydride to propargyl alcohol selectively affords the Z-alkenylaluminate 11, which can be reacted with tributyltrifluoromethylsulfonyloxy)stannane (X=OTf) to give (Z)-3-(tributylstannyl)prop-2-en-1-ol (12, R1=H) in 80% yield (Scheme 6).[‌15‌] The hydroalumination of substituted prop-2-yn-1-ols can be used to prepare 3-substituted 3-(tributylstannyl)prop-2-en-1-ols 12 when tributylmethoxystannane (X=OMe) is used (lower yields are obtained with tributyltrifluoromethyl(sulfonyloxy)stannane or tributylchlorostannane) (Scheme 6).[‌16‌] Yields are in the range 1374% for a wide variety of R1 groups (alkyl, aryl, heteroaryl, ethers) and triethylamine should be added to the solvents used for chromatographic purification of the products in order to prevent protiodestannylation.[‌16‌] An alternative method for the preparation of γ-hydroxyalkenylstannanes, such as 13, is to use dichlorobis(η5-cyclopentadienyl)titanium to catalyze the hydromagnesiation of a propargyl alcohol, with subsequent trapping of the alkenylmagnesium intermediate with tributylchlorostannane (Scheme 6).[‌17‌] This method relies on the coordination of the metal to the oxygen to control the regio- and stereochemistry of the final alkenylstannane.

Meeeee 8 Meeeeeeeeeeeeeee eee Meeeeeeeeeeeeeeee ee Meeeeeeee Meeeeeee[‌88‌‌88‌]

Meeeeeeeeeeeeee eeee eeeeeeeeeeeeeeee eeeeeeeee ee eee eeeeeeee e eeeeeeeeee eeeeee eee eee eeeeeeeeeeeeeee eeeeeeeee ee M-eeeeeeeeeeeeeeee (Meeeee 8). Mee eeeeeeeeeeeeeeee ee eeeeeeeeeeeeee eeeeeee eee eeeeee eeee eee eeeee Meeeeeee'e eeeeeee eeeee ee eee eeeee- eee eeeeeeeeeeeeeee eeeeeeeee ee eeeeeee- eee 8,8-eeeeeeeeeeeeeeee 88 eee eee eeeeeeeeeeeeeee eeee eeeeeeeee ee eee eeeeee eeee eeeeeeeee ee eeeeeeeeeeeee 88. Meeeeeee ee eee eeeeeee eeeee eeee eeeeeeeee ee eee eeeeeeeeeeeeeee eee ee ee eeee eeee eeeeeeeeeee, eee eee eeeeeeeeeeeeeee eeee eeeeeeeeeeeeeeeeeeeeee ee eeee eeeeeeeee eeeeeeee ee eeee eeee eeeeeeeeeeeeeeeeeeeeee eeeeeee ee eee eeeeeeee ee eee MeM eeee.[‌88‌]

Meeeeeeeee eeeeeeeee ee M-eee-8-eeeeeeeeeeeeeeeeee (eeeeee ee eee eeeeeeeeeeeee ee eee-8-eeee eeee e eeeeeeeeeeeee) eeee eeeeee eeeeeeeee eee eeee eeeeeeeeeeeeeeeeeeeeee ee eee eeeeeeee ee e eeeeeeeee eeeeeeee ee (eeeeeeeeeeeeeee)eeeeee(MM) eeeee eee eeeeeeeeeeeee M-eeeeeeeeeeeeeee 88 ee eeeeeeeee eeeee (Meeeee 8).[‌88‌]

Meeeee 8 Meeeeeeeeeee ee Meeeeee Meeeeeeeee eee Meeeeee[‌88‌,‌88‌]

Meeeeeeeeeee Meeeeeeee

8-(8-Meeeeee)-8-(eeeeeeeeeeeeeee)eeee-8-ee-8-ee (88, M8=8-eeeeeee); Meeeeee Meeeeeeee:[‌88‌]

MeMMe (8.88e, 8.8eeee) eee eeeee ee e 8M eeee ee MeMeM8 ee MMM (88.8eM). Mee eeeeeee eee eeeeee ee 8°M, eeeeeeeee e eeee ee 8-(8-eeeeeee)eeee-8-ee-8-ee (8.8e, 88.8eeee) ee MMM (88eM) eee eeeeee eeeee. Mee eeeeeeeee eeeeeee eee eeeeeee eee 8e ee 8°M, MeMMe (8.8eM) eee eeee eeeee, eee eee eeeeeee eee eeeeeee eee 88eee eeeeeee eeeeeee. Mee eeeeeee eee eeee eeeeee ee 8°M eeee eeee, Me8MeMMe (88.8eM, 88.8eeee) eee eeeee, eee eee eeeeeee eee eeeeee ee e eeeeeeeeeeee (8°M). Meeee 8e, MeMM (88eM) eee eeeee, eee eee eeeeeee eee eeeeeee eee 8e ee ee eee eeee eeeeee eeee M8M (888eM). Mee eM eee eeeeeeeee eeeeeeee ee 8 ee eee eeeeeeee ee eee MMe eee eee eeeeeee eee eeeeeeeee eeee Me8M (8×888eM). Mee eeeeeeee eeeeeeee eeeeeeee eeee eeeee (Me8MM8) eee eee eeeeeee eee eeeeeeeeee ee eeeee. Meeeeeeeeeeeee ee eee eeeeeee (eeeeee eee, eeeee eeeeeeeee eeeee/eeeeeee 88:8) eeee eee eeeeeee; eeeee: 88.88e (88%).