Science of Synthesis

Pineschi, M.; Boldrini, C., Science of Synthesis: Advances in Organoboron Chemistry towards Organic Synthesis, (2019) 1, 204.

Five-membered cyclic vinyl carbonates react with both bis(pinacolato)diboron (‌2‌) and bis[(pinacolato)boryl]methane (‌43‌) in a copper-catalyzed process. The two reactions follow an SN2′ pathway, with cleavage of the allylic C—O bond and ring opening of the cyclic carbonate. Interestingly, the ring opening is followed by loss of carbon dioxide, generating a free hydroxy moiety.[‌13‌] The reaction with bis[(pinacolato)boryl]methane (‌43‌) is catalyzed simply by copper(I) chloride and cesium carbonate, without the need for a ligand (‌Scheme 13‌). The cumulative yields for the borylated products ‌49‌ with aryl substituents are high, but the E/Z ratios are relatively low (around 4:1). The presence of electron-poor or electron-rich aryl groups on the vinyl carbonate substrates ‌48‌ does not seem to have a significant effect on the reaction. No examples with alkyl substituents were reported.[‌13‌]

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‌Meeeeeeeeee 88‌

M8	Meeee (%)		Mee
	(M)-‌88‌	(M)-‌88‌
Me	88e		[‌88‌]
8-MM8M8	88	88	[‌88‌]
8-MeMM8M8	88	88	[‌88‌]
8,8,8-(MeM)8M8M8	88	–	[‌88‌]
	88	88	[‌88‌]
8-eeeeeee	88	88	[‌88‌]
8-eMeM8M8	88	88	[‌88‌]
MM=MM8	88	–	[‌88‌]

e Meeeeeee ee ee eeeeeeeeeee 8:8 M/M eeeeeee.

Meeeeee eeeeeeeeee [eeeeee(M) eeeeeeee eee eeeeee eeeeeeeee] eeeeeeee eee eeee eeeeeee eeee eee(eeeeeeeeee)eeeeeee (‌8‌), eee eeeeeeee ee e eeeeee ee eeeeeeee ee eeeeee eeeeeeee eeeeeeeeee, eeeeeee M eeeeeeeeeee, eee eeeee eeeeeeeeeee ee eee eeeeeeee eeeeeeee. Mee M-eeeeeeeeeeee eeeeeee 8,8-eee(8,8-eeeeeeeeeeeeeeeee)-8,8-eeeeeeeeeeeeeee-8-eeeeeee (MMMe) eeeee eee eeee eeeeeee (‌Meeeee 88‌).[‌88‌] Mee eeeeeeee ee eeeeeeee-eeee ee eeeeeeee-eeee eeee eeeeee ee eee eeeee eeeeeeeee eeeeeeeeee ‌88‌ eeee eee eeee ee eeee e eeeeeeeeeee eeeeee ee eee eeeeeeee, eee eeeee-eeeeeeeeeee eeeeee eeeeeeeeee ee eee eeeee.

‌Meeeee 88‌ Meeeee-Meeeeeeee Meee Meeeeee ee Meeeee Meeeeeeeee eeee Mee(eeeeeeeeee)eeeeeee[‌88‌]

‌Meeeeeeeeee 88‌

M8	Meeee (%)	Mee
Me	88 (88)e	[‌88‌]
8-MM8M8	88	[‌88‌]
8-MeM8M8	88	[‌88‌]
8-MeMM8M8	88	[‌88‌]
	88	[‌88‌]
8-MeMM8M8	88	[‌88‌]
	88	[‌88‌]

e Meeee ee eeee-eeeee eeeeeeee.

Meee 8,8-eee[(ee-eeee-eeeeeeeeeeeeee)eeeeee]eeeeeee (‌88‌) ee eeee ee eeeeee, eee eeeeeee eeeeeeeeee ee eeeee/eeee-eeeeeeeeeee eeeeee eeeee eeeeeeeeee ‌88‌ eeeeeeeee eee eeeeeee eeeeeeee ee eee M-eeeeee, eeeee eeeeeeeee eeeeeeeeeee ee eeeeee eeeeeeeeee ‌88‌ (‌Meeeee 88‌).[‌88‌] Mee eeeeeeeee ee eeee eeee ee eeeeeeeee ee eeeeeeee eeee eee eee M-eeeeee ee eee eeeeeee eeeeeeee eeeeeee eee eeeeeeeeeeee ee eee eeeeeeee eeeeee eee eeeeeee eeeeee eee eee eeeee eeeee eeee eeeeeeee eeeeeeeee eee eeee eee eeeeeee eeeeeee eeeeeeeeee e eeeeeeeeee eeee eeeeeee eee eeeeeeeeeee eeee eeeeeee. Meeeeeeeee eeee eeeee eee eeeeeeeeee ee eeeeeee eeeeeeeee eee ee eeeeeeeeeee-eeeee eeeee[‌88‌–‌88‌]

Meeee, eeeeee ee ee eeeeeeeeeee eeeeee eee eee eeeeee-eeeeeeeee eeee eeeeeee ee eeeeee eeeeeeeeee eee eeeee eee eeeeeeeeeeeeee eeeeeee ee eee eeeeeeeee ee eee M- ee M-eeeeee.

‌Meeeee 88‌ Meeeee-Meeeeeeee M-Meeeeeeee Meeeeeeee eeeeeee Mee(eeeeeeeeee)eeeeeee eee Meeeee Meeee Meeeeeeeee Me Meee Meeeeeeeee[‌88‌]

‌Meeeeeeeeee 88‌

Meee eeeeeeeee eee eee eeeeeeeeee eeee eeeeeee ee eeeeee eeeeeeeeee, eeeee eeeeee eee(eeeeeeeeee)eeeeeee (‌8‌) ee eee[(eeeeeeeeee)eeeee]eeeeeee (‌88‌), eee ee eeeeeeee ee eeeeeeeee eeeeee, eeeeeeee eee eeeeeeeeeeeee eee-8-eee-8,8-eeeee eee eeee-8-eee-8,8-eeeee, eeeeeeeeeeee ee eeeeeeee eeeeee.[‌88‌]

Meeeeeeeeeee Meeeeeeee

Meeeeeeeeeeeeeeeee ‌88‌; Meeeeee Meeeeeeee:[‌88‌]

Meeee eeeee, ee eeee-eeeee Meeeeee eeee eeeeee eeee e eeeeee eeeeee eee eeeeeeee eeee e eeeeeeee eeeeeee eee eee eeeeeee eeee e eeeee eeeeeeeee ‌88‌ (8.8 eeee). Meee, eee[(eeeeeeeeee)eeeee]eeeeeee (‌88‌; 88 ee, 8.88 eeee) eee MeMe (8.8 ee, 8.888 eeee, 8 eee%) eeee eeeee, eeeeeeee ee eeeee MeMM (8.8 eM) eee Me8MM8 (88 ee, 8.8 eeee, 88 eee%). Mee eeeeeee eee eeeeeee ee ee eeeeeeeee eee eeee eeeeeeee eeeeeee e eeeee eee ee Meeeee, eeeeeee eeee MM8Me8. Mee eeeeeee eee eeeeeeee ee eeeee eeeeeeeeeeeeee (eeeeee eee, eeeeeee/MeMMe).

Meeeeeeeeeeeee ‌88‌; Meeeeee Meeeeeeee:[‌88‌]

Meeee eeeee, ee eeee-eeeee Meeeeee eeee eeeeee eeee e eeeeee eeeeee eee eeeeeeee eeee e eeeeeeee eeeeeee eee eee eeeeeee eeee e eeeee eeeeeeeee ‌88‌ (8.8 eeee). Meee, eee(eeeeeeeeee)eeeeeee (‌8‌; 88 ee, 8.88 eeee), MeMe (8.8 ee, 8.888 eeee, 8 eee%), eee 8,8-eee(8,8-eeeeeeeeeeeeeeeee)eeeeeeeeeeeee eeeeeeee (MMMe•MMe; 88 ee, 8.888 eeee, 88 eee%) eeee eeeee, eeeeeeee ee eeeee MeMM (8.8 eM) eee Me8MM8 (8.8 ee, 8.88 eeee, 88 eee%). Mee eeeeeee eee eeeeeee ee ee eeeeeeeee eee eeee eeeeeeee eeeeeee e eeeee eee ee Meeeee, eeeeeee eeee MM8Me8. Mee eeeeeee eee eeeeeeee ee eeeee eeeeeeeeeeeeee (eeeeee eee, eeeeeee/MeMMe).

8,8-Meeeeee-8M-8,8-eeeeeeeeee-8-eee ‌88‌; Meeeeee Meeeeeeee:[‌88‌]

Meeee eeeee, ee eeee-eeeee Meeeeee eeee eeeeee eeee e eeeeee eeeeee eee eeeeeeee eeee e eeeeeeee eeeeeee eee eee eeeeeee eeee e eeeee eeeeeeeee ‌88‌ (8.8 eeee). Meee, eee(eeeeeeeeee)eeeeeee (‌8‌; 88 ee, 8.88 eeee), MeMe (8.8 ee, 8.888 eeee, 8 eee%), eee 8,8-eee[(ee-eeee-eeeeeeeeeeeeee)eeeeee]eeeeeee (‌88‌; 8.888 eeee, 88 eee%) eeee eeeee, eeeeeeee ee eeeee MeMM (8.8 eM) eee Me8MM8 (8.8 ee, 8.88 eeee, 88 eee%). Mee eeeeeee eee eeeeeee ee ee eeeeeeeee eee eeee eeeeeeee eeeeeee e eeeee eee ee Meeeee, eeeeeee eeee MM8Me8. Mee eeeeeee eee eeeeeeee ee eeeee eeeeeeeeeeeeee (eeeeee eee, eeeeeee/MeMMe).

References