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4.4.40.14 Method 14: From 1,3-Dienes by Hydrosilylation

DOI: 10.1055/sos-SD-004-00909

Sarkar, T. K.Science of Synthesis, (20024855.

Z-Allylsilanes are available by transition-metal-catalyzed 1,4-hydrosilylation of conjugated acyclic dienes,[‌114‌‌116‌] as exemplified by the preparation of (Z)-59[‌116‌] (Scheme 27). In addition, regioselective synthesis of (Z-2-ethylidenecycloalkyl)silanes, for example, 60, is possible by hydrosilylation of 1-vinylcycloalkenes with dichloromethylsilane (Scheme 27).[‌117‌] The use of a chiral palladium catalyst allows the synthesis of enantiomerically enriched acyclic allylsilanes.[‌118‌,‌119‌] For example, enantiomerically enriched 1,3-unsymmetrically substituted allylsilanes, such as 61, have been prepared by catalytic asymmetric hydrosilylation of (E)-1-phenylbuta-1,3-diene with fluorodiphenylsilane in the presence of a palladium catalyst, generated in situ from the (η3-allyl)chloropalladium(II) dimer and (R)-2-diphenylphosphino-2-hydroxy-1,1-binaphthyl [(R)-MOP], followed by treatment with methyllithium (Scheme 27).[‌118‌] The regio- and enantioselectivities in this case have been found to be strongly affected by the structure of the hydrosilane and the phosphine ligand.[‌118‌] For example, reversal of enantioselectivity occurs in the case of 61 when the tert-butyldimethylsilyl ether of (R)-2-diphenylphosphino-2-hydroxy-1,1-binaphthyl is used.[‌118‌] For asymmetric hydrosilylation of cyclic 1,3-dienes, (R)-3-diphenylphosphino-3-methoxy-4,4-biphenanthryl [(R)-MOP-phen] is a more efficient chiral ligand than the related (R)-MOP ligands for high enantioselectivity, as shown by the preparation of chiral silane 62.[‌120‌]

Meeeee 88 Meeeeeeeeeee ee Meeeeeeeeeeeeee ee 8,8-Meeeee[‌888‌‌888‌,‌888‌]

Meeeeeeeeeee Meeeeeeeee

[(M)-Mee-8-eeee]eeeeeeeeeeeeeee [(M)-88]:[‌888‌]

MMeMe8 (88e, 8.888eee) eee Me(MMe8)8 (8.88e, 8.8eeee) eeee eeeeee ee ee eeeee-eeeeee eeeeeeeee (888eM). Meeeeeeeeeee ee eeee-8,8-eeeee (88eM, 8.88eee) eeee eee eeeeee ee 88°M, eeeeeeee eee 8e, eee eee eeeee eeeeee eeee eee eeeeeee; eeeee: 88.88e (88%).

Meeeeeeeeeeeee[(M,M)-8-eeeeeeeee-8-eeee]eeeeee (88):[‌888‌,‌888‌]

M 88-eM eeeeee eeee eeeeeeeeee e eeeeeeee eeeeeeee eee eee eeeeeee eeee (M)-MMM (88ee, 8.888eeee), [Me8(η8-eeeee)8Me8] (8.8ee, 8.888eeee ee Me), 8-eeeeeeeeee-8,8-eeeee (8.88e, 8.8eeee), eee MMeMe8M (8.88e, 8.8eeee) eeeee eeeee, eee eee eeeeeee eee eeeeeee ee ee (ee 88°M) eee 88e. Meeeee MeMe ee Me8M eee eeeee ee eeeeeee eee MeM eeeee eeee ee MeMe eeeee. Meeeeeeee eeee eee. ee MM8Me, eeeeeeeeee, eeeeee (Me8MM8), eee eeeeeeeeeeeee, eeeeeeee ee eeeeeeeeeee MMM (eeeeee eee, eeeeee) eeee eee eeeeeee [88% ee, ee MMMM (Meeeee Meeeeeeee-MM, eeeeee)]; eeeee: 8.88e (88%); [α]M 8.88 (e 8.88, MMMe8).

(M)-Meeeeeeee(eeeeeeeee-8-eeee)eeeeee (88, e=8); Meeeeee Meeeeeeee:[‌888‌,‌888‌]

Meeee eee M8, MMeMe8 (8.8eM, 8.8eeee) eee eeeee ee e eeeeeee ee [Me8(η8-eeeee)8Me8] (8.88ee, 8.8888eeee Me), (M)-MMM-eeee (8.88ee, 8.88888eeee), eee eeeeeeeeee-8,8-eeeee (8.888e, 8.8eeee) ee 8°M. Mee eeeeeee eee eeeeeee ee 88°M eee 8e. Mee eeeeeeeeee ee eee eeeeeeee eee eeeeeeeee ee MM eeeeeeee. Me eeeee eeee-ee-eeee eeeeeeeeeeee ee eee eeeeeee eeee eee eeeeeee (88% ee); eeeee: 8.88e (88%); ee 888°M/88Meee.

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