Table 1.

Investigation into the linear allylic oxidation reaction to form the hexose precursor 6.

Entry	DMSO/CH2Cl2 Molarity [M]	Quinone (Q)	Acid 5 (equiv)	Yield [%][c]
1	0.33	BQ	15	23[d]
2	0.33	BQ	15	45
3	0.33	PhBQ	15	55
4	0.6	PhBQ	10	66
5	1.0	PhBQ	5	67
6[b]	2.0	PhBQ	3	75
7[b]	2.0	PhBQ	3	71[e]
8	2.0	PhBQ	3	63[f]
9	3.0	PhBQ	1.5	50

^[a]DMSO/CH₂Cl₂ (3.2:1).

^[b]Linear to branched allylic ester and E/Z ratios were determined by HPLC for the material obtained from entries 6 and 7 on comparison with branched or acetonide-free E and Z standard compounds: linear/branched >300:1, E/Z =30:1 and 36:1 (for entries 6 and 7, respectively).

^[c]Yield of isolated product from the reactions carried out on a 1 mmol scale (4, 262 mg). Yields and selectivities represent an average of at least 2 runs.

^[d]With no DIPEA added.

^[e][Pd(CH₃CN)₄](BF₄)₂ (10 mol%), 13% of 4 was recovered.

^[f]Pd(OAc)₂ (5 mol%). Bn =benzyl, DIPEA=N,N-diisopropylethylamine, MS =molecular sieves.