Science of Synthesis

Suginome, M.; Ito, Y., Science of Synthesis, (2004) 19, 450.

The ring-opening reaction of epoxides ‌12‌ with silyl cyanides can take two courses, nitrile formation or isocyanide formation (‌Scheme 9‌). The use of aluminum trichloride,[‌21‌] diethylaluminum chloride,[‌22‌] or potassium cyanide/18-crown-6[‌23‌] as promoters leads to epoxide ring opening with exclusive formation of nitriles. Moreover, titanium(IV) isopropoxide mediates the ring opening of the epoxide ring with preferential formation of nitriles over isocyanides.[‌24‌] In sharp contrast, the use of zinc(II) iodide as a Lewis acid promoter gives the corresponding β-siloxy isocyanide selectively (‌Table 1‌); an example is the synthesis of isocyanide ‌13‌ (entry 3).[‌25‌–‌28‌] The ring-opening reaction is highly stereospecific: a perfect stereochemical inversion occurs at the epoxide carbon atom that undergoes the nucleophilic attack. Highly regioselective ring-opening reactions of substituted cyclohexene oxides are directed by neighboring hydroxy or protected hydroxy groups, leading to the formation of highly functionalized cyclic compounds (entries 10 and 11).[‌27‌] 7-Oxabicyclo[4.1.0]hepta-2,4-diene (1,3-cyclohexadiene epoxide) undergoes a highly regioselective ring opening under the reaction conditions (entry 12).[‌25‌] The products are readily converted into β-amino alcohols by hydrolysis. With regard to the substituents of the silyl groups of the silyl cyanides, the trimethylsilyl group allows a much faster reaction with epoxides than does the tert-butyldimethylsilyl group.

‌Meeeee 8‌ Meeeeeee ee Meeeeeee eeee Meeee Meeeeeee[‌88‌–‌88‌]

‌Meeee 8‌ Meeeeeeeee Meeeeeeee eeeeeee Meee Meeeeee ee Meeeeeee eeee Meeee Meeeeeee ee eee Meeeeeee ee Meee Meeeeee[‌88‌–‌88‌]e

Meeee	Meeeeee ‌88‌	M8M8M8Me	MeM8 (eeeee)	Meee (Meeeeee)	Meeeeee	Meeee (%)	Mee
8		MMM	MeMe8 (8.88)	88°M (MMMe8)		88	[‌88‌]
8		MMM	MeM8 (8.888)	eeeeee (MM8Me8)		88	[‌88‌]
8		MMMMM	MeM8 (8.88)	eeeeee (MM8Me8)		88	[‌88‌]
8		MMM	MeM8 (8.888)	eeeeee (MM8Me8)		88	[‌88‌]
8		MMM	MeM8	eeeeee (MM8Me8)		88	[‌88‌]
8		MMM	MeM8	eeeeee (MM8Me8)		88	[‌88‌]
8		MMMMM	MeM8 (8.88)	eeeeee (MM8Me8)		88	[‌88‌]
8		MMM	MeM8	eeeeee (MM8Me8)		88	[‌88‌]
8		MMMMM	MeM8 (8.88)	eeeeee (MM8Me8)		88	[‌88‌]
88		MMM	MeM8 (8.888)	eeeeee (MM8Me8)		88e88e	[‌88‌]
88		MMM	MeM8 (8.888)	eeeeee (MM8Me8)		88e88e	[‌88‌]
88		MMMMM	MeM8 (8.88)	eeeeee (MM8Me8)		88	[‌88‌]

e Mee ‌Meeeee 8‌.

e M8 = M.

e M8 = MMM.

Mee eeeeeeee eeeeeeeeee eeeeeeeee eeee(MM) eeeeee eee eeee eeeeeeeeee ee eee eeee-eeeeeee eeeeeeeee ee eeeeeeee ‌88‌ (‌Meeeee 88‌).[‌88‌,‌88‌] Mee eeeeeeeee eeeeee γ-eeeeee eeeeeeeeeee ‌88‌, eeeee eee ee eeeeeeeeeee eeee γ-eeeee eeeeeeee ee eeeeeeeeee.

‌Meeeee 88‌ Meeeeeee ee Meeeeeee eeee Meeeeeeeeeeeee Meeeeee ee eee Meeeeeee ee Meee(MM) Meeeee[‌88‌,‌88‌]

‌Meeeeeeeeee 88‌

Meeeeeeeeeee Meeeeeeee

8-(eeee-Meeeeeeeeeeeeeeeeee)eeeeeeeeee Meeeeeeeee (‌88‌); Meeeeee Meeeeeeee:[‌88‌]

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

Meeeeeeeeee eeeee (8.8 e, 88.8 eeee) ee MM8Me8 (88 eM) eee eeeee ee e eeeeeeeee eeee ee (MMMMM)MM (8.88 e, 88.8 eeee) eee MeM8 (888 ee, 8.88 eeee) ee MM8Me8 (88 eM). Mee eeeeeee eee eeeeeeee eee 88 e, eeeeee, eee eeeeeeee eeeeeee e eeeeee eee eeee. Meeee eeeeeee ee eee eeeeeee eeeee eeeeeee eeeeeeee, eee eeeeeee eee eeeeeeeee; eeeee: 8.88 e (88%); ee 88–88°M; ee 88–88°M/8 × 88−8 Meee.

8-(Meeeeeeeeeeeeee)eeeeee Meeeeeeeeee ‌88‌; Meeeeee Meeeeeeee:[‌88‌]

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

Meeeeee ‌88‌ (8.8 M ee MM8Me8, 8.8 eeeee) eee eeeee eeeeeeee eeee 8.8 e ee e eeeeeeeee eeee eeeeeeeeee MMMMM (8.8 M ee MM8Me8, 8.8 eeeee) eee MeM8 (8.88 eeeee). Meeee ee eeeeeeeeeee eeeeee ee eeeeeeeee, eee eeeeeee eee eeeeeeee eeeeeee e eeee ee eeeeee eee, eee eeeeeee eee eeeeeee, eee eee eeeeeee eee eeeeeeee ee eeeeeeeeeeee; eeeee: 88–88%.

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